<P> The Treaty of Guadalupe Hidalgo and another treaty in 1884 were the agreements originally responsible for the settlement of the international border, both of which specified that the middle of Rio Grande was the border--irrespective of any alterations in the channels or banks . The Rio Grande shifted south between 1852 and 1868, with the most radical shift in the river occurring after a flood in 1864 . By 1873 the moving river - center border had cut off approximately 600 acres (2.4 km) of Mexican territory in the El Paso - Juarez area, in effect transferring the land to the United States . By a treaty negotiated in 1963, Mexico regained most of this land in what became known as the Chamizal dispute and transferred 264 acres (1.07 km) in return to the United States . Border treaties are jointly administered by the International Boundary and Water Commission (IBWC), which was established in 1889 to maintain the border, allocate river waters between the two nations, and provide for flood control and water sanitation . Once viewed as a model of international cooperation, in recent decades the IBWC has been heavily criticized as an institutional anachronism, by - passed by modern social, environmental and political issues . </P> <P> The economic development of the border region on the Mexican side of the border depended largely on its proximity to the United States, due to its remoteness from commercial centers in Mexico . Undocumented labor contributes $395 billion to the economy every year . If undocumented labor in the United States was largely Hispanic, it would have the same sized national economy as Sweden and rank ahead of countries such as Switzerland, Austria and Singapore and be bigger, in terms of GDP . Immigration reform has been a huge theme in U.S. politics, in recent years . While the U.S. is in favor of immigration, the increase in undocumented immigration has given border - crossing a negative image . There are around 11.5 million undocumented workers in the U.S. today, and 87% of undocumented immigrants have been living in the U.S. for more than 7 years . Basic rules of macroeconomics indicate that as long as there are better opportunities existing in the U.S., immigration and the number of undocumented immigrants will continue to rise . Local economies that develop on the Mexican side capitalize not only on available skills but also on available, usually discarded, materials . Small businesses trade in clothes that are purchased by the pound and cardboard from the United States . Some items, like the used tires found everywhere along the border, are made into certain items that support local economies and define a border . </P> <P> During the years of Mexican President Porfirio Díaz, between 1876 and 1910, the border communities boomed, due mostly to close ties to the United States, and the Mexican government's support for financial investments from the United States . Railroads were built that connected the northern Mexican states more to the United States than to Mexico and the population grew tremendously . The mining industry also developed, as did the United States' control of it . By the early 20th century companies from the United States controlled 81% of the mining industry and had invested five hundred million dollars in the Mexican economy overall, twenty - five percent of it in the border regions . </P> <P> The Mexican Revolution, caused at least partially by animosity toward foreign ownership of Mexican properties, began in 1910 . The Revolution increased the political instability in Mexico, but did not significantly slow United States investment . It did reduce economic development within Mexico, however, and the border regions reflected this . As the infrastructure of communities on the United States side continued to improve, the Mexican side began to fall behind in the construction and maintenance of important transportation networks and systems necessary to municipal development . </P>

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