INTRODUCTION

This article analyzes the population growth of Tijuana during the 1920s, a period in which the border town’s population grew from 1 028 to 8 348 inhabitants. Regional historiography has explained this phenomenon as a consequence of the Prohibition in the United States between 1921 and 1933, which prohibited the production and commercialization of alcoholic beverages. This event is often addressed in an anecdotal way by highlighting the effects of Prohibition in the locality. However, there is no detailed analysis of the process and its relation to the population growth of the towns in Baja California during the last decades of the 19th century (^{Magaña Mancillas, 2004}; ^{Cruz González, 2015}) and the first four decades of the 20th century (^{Piñera Ramírez & Martínez Zepeda, 1994}; ^{Cruz González, 2007}; ^{García Searcy, 2019}).

The aim is to answer three questions: Was the population growth of Tijuana a specific phenomenon of the locality or was it a widespread process along the border? What were the main characteristics of Tijuana’s population during the 1920s? And where did the migration that populated this border municipality come from? The findings show that it was not a widespread phenomenon along the Mexico-U.S. border, but only occurred in the municipalities adjacent to the major U.S. border cities: San Diego and El Paso. On the other hand, census information shows that Tijuana had a predominantly male population oriented towards the tertiary sector in terms of employment; it also indicates a significant dispersion of rural population in small localities that were part of the municipal territory. However, there is a limitation in answering the third question because census information on the places of origin of the population is not disaggregated at the municipal level. Therefore, we decided to work with parish records that, although they do not cover the entire decade, locally coincide with the data reported by censuses at the district and territory levels. They show that migration mainly came from the southern district of Baja California, as well as from Sonora and Jalisco.

The article consists of three sections: the first section analyzes the population growth of Tijuana and the border municipalities and localities during the 1920s; the second section reviews the composition and main demographic structures of Tijuana, such as the distribution by sex and age, the Economically Active Population (EAP), and the dispersion of the population among different localities; and the third section presents some findings on the places of origin of the population and possible factors of attraction and expulsion, indicating the scope and limitations of ecclesiastical sources.

THE POPULATION OF TIJUANA, THE BORDER AND PROHIBITION

The population growth of Baja California has been the subject of research since the 1950s. The pioneering work of ^{Lemoine Villicaña (1959)}, which explains the demographic processes of the peninsula from the colonial period to the 20th century, paved the way for research focused on delimited temporal and spatial issues. Some of these have been approached from demographic perspectives, such as that of ^{Canales Cerón (1995)}, which sought the “foundational matrix” of modern population growth in Baja California; or the study by ^{Zenteno (1995)}, which placed the demographic change of this city within the framework of relations between Mexico and the United States; likewise, the work of ^{Piñera Ramírez and Martínez Zepeda (1994)} recovers useful materials for the historical demography of the border region in the early 20th century.

Starting in the 2000s, works on the subject with historical approaches were produced, such as that of ^{Trejo Barajas (2005)}, where the decline and growth of the population in the territories that correspond to the current state of Baja California Sur in the 19th and 20th centuries are analyzed. The interdisciplinary efforts resulting from historians’ incursion into the field of demography are also notable. This is the case of ^{Magaña Mancillas (2004}, ²⁰¹⁰⁾, who addressed a similar temporality as Trejo Barajas, but focused on the area of the current state of Baja California. Similarly, ^{Cruz González (2015)} analyzed the demographic dynamics of the second half of the 19th century and the 1930s (^{Cruz González & Urbalejo Castorena, 2018}; ^{Cruz González, 2007}), while ^{García Searcy (2019)} addressed this topic for the 1940s. Recently, ^{Magaña Mancillas (2020)} wrote a review of the studies on the population growth of Baja California.

This study focuses on the population growth of Baja California because it is one of the regions that experienced rapid growth during the 20th century. This phenomenon, more than being anchored in pre-existing urban formations - as is the case in large metropolitan areas - was the result of the emergence of new cities throughout northern Mexico (1870-1930), the development of new agricultural areas, and population movements that took place between Mexico and the United States at the end of the 19th century (^{Aboites Aguilar, 2010}). Situating events such as the explosive growth of Tijuana during the 1920s within a broader framework allows for the questioning of some commonplaces of local and regional history. In this case, we will problematize the correlation between Prohibition and the population growth of Tijuana.

The prohibition of alcohol in the United States was established in 1921 when the eighteenth constitutional amendment, presented in 1919 by Andrew Volstead, was ratified by Congress (^{Const. 18th Amendment, 1919}). It ended in 1933 when the amendment was repealed (^{Const. 21st Amendment, 1933}), in the context of the Great Depression. It was a paradoxical time. The “Volstead Amendment”, as it came to be called, reflected the concerns that temperance groups had been promoting since the late 19th century, seeking to regenerate American society and regulate not only the consumption of alcohol, but a range of activities they considered harmful, such as prostitution, gambling, and other forms of entertainment. This legislation came into effect in a context of economic prosperity, while a consumer society eager for entertainment and fun spaces was consolidating, especially in urban environments.

During Prohibition—as this era was also known—alcohol consumption was not eradicated, but it did manage to transform many spaces and forms of mainly male sociability. One of its effects was the emergence of mafias dedicated to the production, distribution, and smuggling of alcoholic beverages. Although it became popular, Prohibition was seen as a problem in the 1930s and its repeal was one of Franklin D. Roosevelt’s campaign promises, as part of a program aimed at alleviating the effects of the economic crisis that began in 1929 (^{Rorabaugh, 2018}; ^{Slavicek, 2009}; ^{Okrent, 2010}; ^{Kassens, 2019}).

The historiography of northern Mexico has analyzed the effects of Prohibition on towns and border regions. In some cases, it has confronted stereotypes produced by prohibitionist perspectives that classify Mexican towns as centers of vice where Americans can access what is prohibited in their own country—something particularly visible in Tijuana—.3 However, there are also more analytical records that account for the social, political, and economic transformations that this situation fostered.⁴ Among other things, it is a phenomenon that coincided with the rise to power of the Sonoran group, the winners of the Mexican Revolution, which implied some paradoxes. These were governments that, at least in the discursive realm, sympathized with the temperance measures promoted in the United States.⁵ However, the military officials who came to power found in this context the possibility of carrying out valuable business ventures. Abelardo L. Rodríguez is one of the most studied cases, as he was appointed governor of Baja California during the 1920s and was said to be the richest man in the country by the following decade (^{Gómez Estrada, 2007}). However, the transformations that took place in border towns were not limited to the governments and business elites.

Tijuana experienced its most rapid growth during that decade. The 1921 census reported just over 1 000 inhabitants, and the 1930 census recorded more than 8 000; in the territorial demarcation corresponding to the municipality, more than 11 000 were counted. Being a town located on the border with the United States, the most obvious explanation lies in the effects of Prohibition, although it is worth asking whether it was a particular phenomenon of Tijuana or one extended throughout the border. Upon reviewing the population of the 16 northern Mexican border cities, it was found that, while Tijuana had the highest growth rate (26% per year), several data points make it necessary to make the explanation more complex.

As can be seen in Table 1, the population of Tijuana was the smallest of the border towns at the beginning of the 1920s. By 1930, it had only surpassed Reynosa, Tamaulipas, and three U.S. towns: Eagle Pass, Texas; Nogales, Arizona; and Calexico, California. San Diego –a city adjacent to Tijuana– was among the most populous on the border; in 1920, with over 74 000 inhabitants, it was second only to El Paso, and in 1930, with nearly 148 000, it became the largest of the U.S. border cities. As for growth rates, there were three Mexican towns with particularly high rates, in addition to Tijuana: Ciudad Juárez (8.2%), Mexicali (9%), and Reynosa (9.6%).

When examining the data at the municipal and county levels, and placing them within the demographic trends at the state and national levels, a complex panorama was found, although with common elements throughout the border, as can be seen in Table 2. The asymmetry between both countries and their bordering states stands out, although with certain nuances. Taking the 1910s as a starting point, it was observed that, while the United States surpassed 100 million inhabitants, Mexico experienced a decrease of approximately one million.⁶ The trend is nuanced when the observation scale is reduced to the bordering states, municipalities, and counties. While Mexico had a rate of -0.5% in the 1910s and 1.6% in the 1920s, the border states grew at 0.3 and 2%. Baja California appears as a peculiar case for being the least populated territory and the state that had the highest growth rate, reporting a constant rate of 8.3%. This contrasts not only with national trends, but also with those of the border states, as Nuevo León and Chihuahua reported negative rates and, in the rest of the states, growth did not exceed the 1.3% reported in Tamaulipas.

Although there was an increase in the 1920s, the growth of these states did not exceed the 2.4% per year reported in Nuevo León.

The U.S. border states also grew above the national average. Texas remained the most populous state on the border, but with rates below 2% annually. By 1930, this state had a population of 5.8 million, followed by California, which reached 5.6 million and had grown 2.6% and 5.2% annually in the previous decades. With some variations, Arizona and New Mexico reached the 1930s with just over 400 000 inhabitants each.

When looking at the figures at the municipal level, we find that the fastest growth, with rates exceeding 5% annually, was concentrated in five municipalities, and not all of them coincide with the previously mentioned localities: Tijuana (22%) and Mexicali (8.3%) in Baja California; Ciudad Juárez (6.3%) and Guadalupe Bravos (5.1%) in Chihuahua; and Acuña (10.77%) in Coahuila.

Tijuana and Ciudad Juarez are two cities whose historiography often gives great importance to the years of Prohibition, which coincides with the presented data. More developed economies tend to increase the consumption capacity of large sectors of the population, which translates into a greater demand for goods and services. Both localities were the most benefited during Prohibition, as they offered entertainment, leisure, and recreational services to this growing sector of American society, which was more numerous in San Diego and El Paso than in the rest of the border.

Tijuana started the 20th century with around 200 inhabitants. From the 1880s, it stood out for the presence of bars and curious shops around the customs house, which led to its foundation. Many of its businesses were linked to American entertainment, which made it an attractive tourist destination across the border. In the early decades of the 20th century, casinos and shows—boxing and cockfighting, horse racing, and bullfighting—as well as hot springs spas, thrived. As a consumer society was already developing in Southern California, the prohibition measures did not represent a new phenomenon, but they did intensify all these activities. It is worth noting that Tijuana was considered “the most visited city in the world” and it was known to have the longest bar in the world—later known as La Ballena—(^{Piñera Ramírez & Padilla, 1991}).

For Ciudad Juarez, the 1920s also meant a critical stage in its trajectory of development and population growth linked to its relationship with El Paso and the southwestern United States. This connection began in the 1880s with the enactment of the Free Zone (1882) and the arrival of the railroad (1884) (^{González, 2009}). Since the beginning of the 20th century, with over 8 000 inhabitants, Ciudad Juarez became an important tourist destination for Americans, who could find licentious forms of entertainment there, such as bullfights, alcohol consumption, and prostitution. Some propose that the Revolution left a positive balance in Juarez, since the arrival of Villa’s troops, the provision of supplies and weapons from the United States, and the transfer of Mexican entrepreneurs who fled from the Revolution, generated a significant economic boost. The first prohibitionist initiatives in Texas appeared in 1914, when authorities attempted to restrict the consumption of opium, morphine, cocaine, and heroin without a medical prescription; it was in 1918 when the prohibition of alcohol was implemented in this state (^{Garcia Pereyra & Madrid Solorzano, 2009}).

Ciudad Juarez began the 1920s with an economy oriented towards the service sector, especially towards American tourism, being the most populated municipality in the northern border of Mexico, with 24 891 inhabitants. Prohibition intensified this activity and led to the production and smuggling of alcohol. There are testimonies that between 1919 and 1920 the city received around 400 000 tourists and although the government of Chihuahua tried to exert some control, its regulatory measures had little effect, while the black legend grew in both countries about the atmosphere of immorality and decadence that prevailed there (^{González, 2009}). Apparently, this perception was promoted by El Paso businessmen and investors who had transferred their capital to that city due to the prohibitions (^{Pinera Ramírez & Verdugo, 1987}). An anecdote that illustrates this dynamic was recovered for the work Visión histórica de la frontera norte de México through an interview that took place in 1985 with a former resident:

Some ejidatarios who had a plot of land outside Ciudad Juarez built a cantina right next to the international border line, and they had the clever idea of opening a window towards the United States side. That way, the American would come, stick his head out the window, have his whiskey or whatever he wanted, and they couldn’t say he was violating the Prohibition Law because he was drinking on the Mexican side! The cantina became famous, they named it El agujero en la pared [The Hole in the Wall], and it had its natural advertisement, everyone talked about it. As it was next to the road to El Paso, many Americans arrived, some very well dressed, they even lined up. (...) These were the situations produced by the famous Volstead Act (^{Pinera Ramírez & Verdugo, 1987, p. 159})

In addition to El Paso and Ciudad Juárez, the municipality of Guadalupe Bravos and Hudspeth County, adjacent to these cities, experienced significant growth. This shows that population growth was not limited to urban areas, but also responded to factors such as the expansion of U.S. markets that demanded agricultural products grown near their main border cities. On the other hand, Table 1 shows that in several of the twin cities, including some of the most populous on the Mexican side— such as Nogales, Nuevo Laredo, and Piedras Negras—there were no major changes. Another locality with significant growth was Reynosa, which went from 2 107 to 4 840 inhabitants. In addition to beer consumption, tourism, and clandestine casinos—since they were not legal in Tamaulipas—, its proximity to the culture of the southeastern United States stands out, where nightclubs with jazz bands and Charleston dancing became popular. A radio station owned by Americans was also inaugurated, as well as a bullring for 5 000 people—a number larger than the population of the town—, and the first red-light district was authorized in 1925 (^{Herrera Pérez, 1998}).

Mexicali also prospered, although not solely due to Prohibition; it was the second most important cotton region in the country and its population growth was more associated with the rural and agricultural sectors. There is evidence that “risky pleasures” also thrived, and that tax revenue from these activities represented a third of the total taxes. In Mexicali, prostitution was regulated and taxed, and there is documentation of many American women crossing to the Mexican side to engage in this activity (^{Schantz, 2011}). In addition, there were significant investments in the brewing industry and other alcoholic beverage industries (^{Almaraz Alvarado, 2007}).

The case of Ciudad Acuña is somewhat unexpected, as the adjacent county in the United States, Val Verde, did not experience significant growth. The tourism that came to this town came from distant places from the border, and its development was due to its strategic location within smuggling routes. We can get an idea of what happened from the testimony of a journalist from the time, also recovered in Visión histórica de la frontera norte de México:

When I first visited the current Ciudad Acuña around 1918, it was nothing more than a small village nestled on the banks of the Las Vacas River (…) Acuña began to prosper when liquor was prohibited in the United States, and it was precisely vice that made it grow. Cantinuchas (little cantinas/bars) were established, and prostitutes arrived, and then Villa Acuña began to have a different aspect. Americans crossed the river eager to drink freely and enjoy themselves to their heart’s content, as with one single dollar they could do so much. Liquor smuggling boomed, and fortunes were made from it. Smuggling was exploited on both sides on a large scale. Many people lived off of it because they earned quite a bit (^{Piñera & Verdugo, 1987, pp. 159-160}).

The parallels and differences in the effects of Prohibition along the border can be corroborated by analyzing the distribution of the EAP of the counties and municipalities that experienced faster growth, as shown in Table 3. The two most populated counties in the United States share a similar profile, with around 70% of their population employed in the tertiary sector, an industrial sector that employed between a quarter and a third of their employees, and an agricultural sector that did not exceed 4%. Although in 1930 Ciudad Juarez had three times the population of Tijuana, they share a similar profile, as the tertiary sector and unspecified population (N/S) accounted for around half of the population, while the secondary sector did not exceed 15% and the primary sector concentrated around a third of the labor force. The other four municipalities have a different profile, as more than 70% of their labor force was employed in the primary sector, the industrial sector did not exceed 5%, and, with the exception of Guadalupe Bravos, the tertiary sector and N/S population accounted for around 20%.

This account allows us to identify Tijuana’s parallels with other border towns but also to locate some important differences. The effects of Prohibition did not affect the border towns in the same way, so both Tijuana’s small population in 1921 and its proximity to San Diego would explain why it was an exceptional case. Likewise, the census information allows us to trace a sociodemographic profile of the population of the municipality of Tijuana during the 1920s, whose main characteristics are presented below.

A DEMOGRAPHIC, TERRITORIAL AND MIGRATORY PROFILE

As mentioned, the origins of Tijuana date back to the second half of the 19th century, in the years following the signing of the Treaty of Guadalupe-Hidalgo and the establishment of the new international border. In 1874, a customs house was established at the Argüello family ranch in the Northern District of Baja California, with the aim of regulating the trade of metals extracted from Real del Castillo by Californian miners. Around it, a small settlement was formed where businesses related to American tourism and entertainment were established. Local historiography places its foundation in 1889, the year in which the dispute between the descendants of the aforementioned family was resolved and the first urban layout was carried out (^{Padilla, 1989}).

The demographic information for these years is scarce, although some documents refer to Tijuana having 257 inhabitants in 1893 (^{Martínez Zepeda, 2003}). The first available census information is from 1900, when Tijuana had the category of “pueblo” (small town) and had 242 inhabitants, 129 men and 118 women. By 1910, the town had 733 inhabitants, 568 men and 165 women (^{Espinoza Meléndez & Ham Chande, 2011}). Far from predicting that, little over a century later, this settlement would become the most populous Mexican city on the border, Tijuana was one of many towns that made up an old missionary corridor that ran from San Diego to El Rosario, and that since the mid-nineteenth century housed small towns that were recorded by the censuses of 1921 and 1930.

One of the difficulties in analyzing population growth during the 1920s is related to the changes in the political division of the territory. In 1874, the peninsula was divided into the Northern, Central, and Southern districts of Baja California. In 1888, two districts were formed: North and South. In 1930, they acquired the status of federal territories, and Baja California became a state in 1953 (^{León-Portilla & Piñera Ramírez, 2010}), while Baja California Sur did so in 1976 (^{Del Río & Altable, 2010}). Regarding the municipal divisions, the 1921 census includes Mexicali, Ensenada, and Tecate, while the 1930 census includes Mexicali, Ensenada, and Tijuana.

These changes represent a problem for tracking the trajectory of Tijuana, which in 1921 belonged to Ensenada, and which, upon acquiring the status of a municipality in 1930, included the territory of the current municipalities of Tecate and Playas de Rosarito. The census information from 1930 allows us to reconstruct the territorial organization of the municipality of Tijuana. Based on the list of localities registered in that year within the municipality of Tijuana, and comparing their population with the previous census, we find that the demarcation as a whole went from 2 213 to 11 271 inhabitants, with an annual growth rate of 20%. These data mean that the town of Tijuana went from concentrating 46% of that population in 1921 to 74% in 1930.

Regarding the classification of the localities, only two of them had the category of pueblo: Tijuana and Tecate. The former had more than 8 000 inhabitants and the latter 566, and together they accounted for nearly 80% of the total population. The 1930 census reports the existence of a camp, the creation of a congregation, and three agricultural colonies during the 1920s, as well as the existence of 49 localities classified as ranchos or rancherías (small, rural settlement), of which only 19 had been registered in 1921 (^{Dirección General de Estadística, 1935}). It is possible that many of them emerged during the decade or that some were simply omitted in the previous census. These data reveal a paradoxical situation regarding the rural population of the municipality of Tijuana in that decade. Although the ranchos and rancherías that were established constituted a significant number in total, they went from concentrating 24% of the population in 1921 to only 12% in 1930. This foreshadowed a process that would take place throughout the twentieth century, in which the growth of Tijuana implied not only population growth, but also the conurbation of many small localities.

As mentioned, one of the main effects of Prohibition was accelerated population growth. In 1921, Tijuana had 1 028 inhabitants—604 men and 424 women—and by 1930 its population had increased to 8 348—4 567 men and 3 817 women—with an annual growth rate of 26.2%. A similar phenomenon occurred during the previous decade in the municipality of Mexicali, which had only 1 612 inhabitants in 1910 but increased to 14 599 in 1921, representing an annual growth rate of 22.2% and a doubling time of 3.2 years. The explanation for this case refers to the development of the Mexicali Valley for commercial agriculture in the early 20th century, resulting from the use of Colorado River water and the increasing demand for cotton.

The population growth of Baja California was the result of internal migration flows that, as shown in graphs 1 and 2, were predominantly male and of working age; the surplus population is located in both cases in the groups between 20 and 40 years old. However, in the 1930 pyramid (graph 2) a certain increase in the age groups under 10 years old can be noticed, which tells us that the natural population growth was beginning to become important.

Source: Own elaboration based on the 1921 population census (^{Departamento de la Estadística Nacional, 1921}).

Graph 1. Baja California Population Pyramid, 1921 

Source: Own elaboration based on the 1930 population census (Dirección General de Estadística, 1935).

Graph 2. Baja California Population Pyramid, 1930 

An indicator of the magnitude of the migration is that the native population of the region represented only 31% of the total during these years; a similar percentage had been born in the geographically closest states. As seen in Table 4, migration from more distant regions was mainly from states in the geographic center of the country, and international migration was predominantly Chinese and American. However, data regarding the latter do not necessarily refer to a migratory flow, but rather to a population dynamic that moved relatively freely across both sides of the border.

There are testimonies from residents who arrived in Tijuana during the 1920s that corroborate how the business boom brought about by Prohibition attracted migrants from the north-central region, as well as a significant foreign population who worked and lived in the area. The following quote was recounted in an interview conducted by Jesus Ortiz Figueroa with Mr. Manuel Bravo González, a Tijuana resident in those years:

I was born in Guadalajara, Jalisco in 1904. I arrived in Tijuana in 1929 by train. I arrived in Nogales and requested permission from the American migration authorities to travel to Tijuana via American territory, on the train that came from Nogales to Tijuana and continued its journey to San Diego and Los Angeles. (…) At that time, there were many foreign workers here in the nightclubs and cabarets; musicians, waiters, cooks, and artists were American, and unions were bringing personnel from the central part of the country (^{Piñera Ramírez & Verdugo, 1987, p. 161}).

MIGRATION AND POPULATION IN ECCLESIASTICAL SOURCES

A problem detected that prevented a more precise account of this migratory process was that census information was not disaggregated at the municipal level. By the 1940s, the work of ^{García Searcy (2010)} remedied this deficiency by using parish records from the Tijuana Cathedral. These records have been a valuable source for historical demography in pre-statistical times, prior to the appearance of census records (^{Hollingsworth, 1983}). The baptismal books of the parish of Our Lady of Guadalupe in Tijuana allow for an approximation of various aspects of life in that locality, although in this case, the focus will be on migration. It should be noted that these sources have significant limitations. The first limitation has to do with its religious nature, which, instead of accurately counting a population, sought to account for souls and sacraments. In addition, in this case it was found that the presence of the Catholic hierarchy in the northern border of Baja California was notably interrupted during the first half of the 20th century, especially due to the suspension of worship during the second half of the 1920s, as a result of the religious conflict that took place in the country.⁷ Considering these limitations, a description of the migratory dynamics of Tijuana during the 1920s is presented based on these records. First, the data related to baptized children are analyzed, and then those of their parents.

Of the 759 baptisms celebrated between 1922 and 1929, 737 took place in the parish of Tijuana, that is, 97%. The remaining 3% refers to nine baptisms performed in Valle de las Palmas in October 1922, six that took place in Tecate in 1924—presumably during a pastoral visit—and six celebrated in San Ysidro and one in San Diego during 1926 in the months prior to the suspension of worship. Given the inevitable question that casts doubt on the precision with which sociodemographic information was recorded during these years, some projections and calculations were made that allowed for a positive evaluation of the quality of such information.⁸

Census data allowed for the calculation of the crude birth rate (CBR) in Mexico and Baja California: at the national level, it was 26.8 births per 1 000 inhabitants in 1921 and 31 in 1930; at the state level, the rate was 29 and 29.5, respectively. For Tijuana, the following exercise was conducted: given that baptismal records only covered three years (1923-1925) and did not coincide with census years, a population projection for every year of the decade was made, using the 1921 and 1930 figures as a reference, in order to calculate the annual growth rate. Subsequently, the number of baptisms recorded in the three complete years was taken as equivalent to the annual number of births, and the CBR was calculated in relation to the estimated population of Tijuana. If the result had been a significantly lower rate than that of the state, it could be thought that the church sources were not very precise, since the number of baptisms would be lower than the number of births. On the contrary, the estimated crude birth rate for Tijuana is around 40 births per 1 000 inhabitants (see Table 5). This may mean that the baptismal records are indeed considerably accurate and that the conditions of this town fostered a higher birth rate than the state average, or that the population projections for these years are lower than the actual population. This latter indicates that possibly, the population of Tijuana at the beginning of the decade was higher than that recorded in the census, or that it grew more rapidly during those years.

The information on the birthplaces of those baptized in Tijuana is valuable for this study. As shown in Table 6, 83.9% of those baptized were born in Mexico, while 16.1% were born in the United States. Of the latter, most were born in the state of California, although four cases of those born in Arizona and one in Texas were also recorded. Of the Mexicans, the majority were born in Baja California (81.4%). There were only eight cases of those born in Sonora, two in Nayarit and Baja California Sur, respectively, and one case in each of the following states: Coahuila, Colima, Federal District, Guanajuato, Jalisco, Tamaulipas, Veracruz, and the State of Mexico. The data on birthplaces speaks of considerable diversity, as only 51.8% of the total were born in Tijuana. While the remaining half includes the main cities and the closest towns both in Baja California and California, none of them represent more than 10% of the total baptized.

Based on this, it can be corroborated that migration from other states mainly occurred in adults rather than children. However, the diversity of Baja California localities suggests that there were not only movements of population within the northern district, but also families from neighboring towns came to Tijuana to baptize their children. Another indication of this is the considerable number of people born in Southern California localities. These data reflect some very particular situations of the trans-border dynamics of the region, such as the attendance of San Ysidro residents and other localities to mass and other religious services in Tijuana. Likewise, the practice of some Mexican families to choose the United States as the territory for their children to be born—a practice that continues to this day—.

The information regarding parents refers more directly to national and international migration.⁹ The relationship between men and women, represented by the masculinity index, allows us to identify that male and female migration followed different patterns. The results show that around one-fifth were born in Baja California, and that most of the migrant population came from the northwest and north-central regions. It makes sense that migration came from the closest region, given the context where communication and transportation development in northwest Mexico was limited. However, the case of Jalisco stands out, as it ranked second in the list and became the main state of origin for migrants to Baja California from the 1950s onward (^{Espinoza Meléndez & Ham Chande, 2011}).

The relationship between migration and gender is also interesting. As shown in Table 7, the population originating from the state and the northwest region was predominantly female, while those coming from more distant regions were mostly male. The only anomalous case recorded is that of Mexico City, not only because it is migration from the most populous city in the country to a peripheral region, but also because it was predominantly female despite the distance.

International migrants represented around eight percent of the records, of which 5.6% were born in the United States—most of them in California, although some came from Arizona, Illinois, Texas, Alabama, Missouri, New Mexico, and Ohio—. The most interesting aspect of these records is the notable predominance of female migration (24 men compared to 41 women), indicating that many of these American-born women were married to Mexican men. The remaining 2.3% came from other countries. There were nine Spaniards, among whom three couples were identified, as well as three men who married Mexican women. There were also four Armenians: two couples who, based on their place of birth, we can infer had been displaced by the genocide perpetrated by the Ottoman Empire in the previous decade. It is noteworthy that they baptized their children in the Catholic Church, even though they belonged to an Eastern rite church. The records also show the registration of four Japanese, two Chinese, and two French men, all married to Mexican women. The presence of three Italians was also recorded, a couple and a man married to a Mexican woman. Similarly, there was a registered Lebanese couple, and finally, a woman originally from Montenegro, married to an American with a Hispanic name. Although baptismal records can be a precise source of information regarding births, they are less accurate in capturing the entirety of a migratory process, since many of the migrants who arrived in Tijuana do not appear in these books, only those who had children and baptized them in the Catholic Church. However, these records allow for a more detailed approximation of national and international migration and provide some clues about the dynamics of a society mainly composed of migrants.

CONCLUSIONS

According to local historiography, behind the fact of a town that went from just 1 000 to over 8 000 inhabitants during the 1920s as a result of Prohibition in the United States, there was a diverse society that was transformed due to national and international migration processes. It is important to differentiate this historical moment from other prohibitions. Although drug policies promoted by the United States have become global, they originated in these years (^{Recio, 2002}). Despite the fact that some post-revolutionary governments campaigned against alcohol, the Prohibition of the 1920s had no effect on Mexican laws, so the difference in legal frameworks between both countries would explain the rise of the referred businesses in Tijuana.

Although Tijuana’s location on the border explains the rapid growth of its population, it was not a generalized process throughout the border, but limited to a few municipalities, of which the most similar case is that of Ciudad Juarez. Both responded to their bordering with the two most populated border cities on the U.S. side, where a consumer society had been formed that saw its entertainment possibilities limited by Prohibition. Likewise, the scarce population of Tijuana at the beginning of the century would explain why its growth rates were the highest on the border, despite higher total numbers in other cases. Ciudad Juarez, compared to Tijuana, doubled its population during this decade, going from 19 000 to more than 39 000 inhabitants. This growth of more than 20 000 inhabitants represented a rate of 8.2% annually, while Tijuana, whose population increased to just over 7 000, grew at a rate of 26%.

Census data allows us to trace a social and demographic profile of the town and the municipality. During the 1920s, as a result of internal migration processes, a predominantly male population with a predominance in working ages was formed in Tijuana. The indicators related to the EAP show that the bulk of the workforce was employed in the service sector, with a profile similar to that of border municipalities such as Juárez, but different from others, such as Mexicali, which were oriented towards the primary sector. It should be noted that this profile, with more than half of the population employed in the tertiary sector at the beginning of the 21st century, corresponded to the distribution of the EAP at the national level, although in the case of Tijuana, it remained constant since the 1930s, despite the growing importance of the industrial sector at the end of the 20th century (^{Espinoza Meléndez & Ham Chande, 2011}).

The limitations of the census sources were found to be that, since the municipality of Tijuana was created during the 1920s, it was difficult to compare the growth not of the locality, but of the demarcation as a whole. This could be remedied by identifying the total number of localities that belonged to the municipality of Tijuana in 1930 and reviewing their population in the 1921 census. This exercise shows that, while the population was concentrated in the municipal seat, many small localities were also created during the 1920s, mainly ranches and rural settlements, but also some agricultural colonies. A second limitation was that the information on the birthplace of the population was not disaggregated at the municipal level, which could be partially addressed by consulting other documentation. In this case, ecclesiastical sources, although not covering the entire decade, are precise in documenting births for several years and, with this, revealing some migratory patterns of the families of the baptized individuals. Although some international migration and mobility can be observed, the bulk of migration was of national origin, predominantly from states in the northwest and, to a lesser extent, from the central-north region.

Baptismal sources also have limitations: although they are precise in documenting births, they are less so in registering migration, as they only include families who had children and baptized them. Therefore, some of the findings generate more questions than answers. For example, some show a predominance of women from the United States, which raises questions about the origin of these migrants—some of whom married Mexicans. One could question whether their move was linked to activities that gained prominence in that decade, such as prostitution—a topic that was more documented for Mexicali and Ciudad Juárez (^{Ruiz Muñoz, 2018})—although the materials consulted do not allow for precise hypotheses. Finally, the parish records draw attention to the role of the Catholic religion in Tijuana in the 1920s, a topic that will be addressed in another research paper.