The Gadsden Purchase: How Tucson Became American

In the summer of eighteen fifty-three, a South Carolina railroad promoter named James Gadsden arrived in Mexico City with a mandate from President Franklin Pierce and a list of possible borders. He was there to buy land.

The United States wanted a southern route for a transcontinental railroad, and the best route ran through territory south of the line established by the Treaty of Guadalupe Hidalgo, which had ended the Mexican-American War five years earlier. That land was still Mexico's. Mexico, under Antonio Lopez de Santa Anna and deeply in need of cash, was willing to negotiate. Gadsden and Santa Anna agreed on a price: ten million dollars for approximately thirty thousand square miles of what is now southern Arizona and southwestern New Mexico.

The treaty was signed December thirtieth, eighteen fifty-three, and ratified by the United States Senate in April of eighteen fifty-four. The border moved south by roughly sixty miles along what is now the Tucson corridor.

Tucson, which had been a Mexican city, became an American one overnight. The residents who woke up Mexican on one side of the ratification and American on the other had not been consulted. Many had deep family roots in the valley, some going back to the Spanish colonial period. They were now citizens of a country they had not chosen. Mexican troops did not actually depart from Tucson until March of eighteen fifty-six, almost two years after the treaty.

The railroad that justified the purchase was built through the corridor in the eighteen eighties. The Southern Pacific connected Tucson to the national rail network in eighteen eighty, transforming a remote adobe presidio town into a regional hub overnight. The Gadsden Purchase bought the land. The railroad built the city.