The Gadsden Purchase, Buying the Bottom Half

In December of eighteen fifty-three, James Gadsden, a South Carolina railroad promoter who had been appointed U.S. minister to Mexico, sat down with President Antonio López de Santa Anna in Mexico City and purchased approximately thirty thousand square miles of land for ten million dollars. That strip of desert and mountain became the southern quarter of Arizona and the southern strip of New Mexico.

The United States wanted it for one reason: a railroad route.

The proposed southern transcontinental railroad needed low-elevation passes through the mountains. The terrain north of the Mexican border, acquired from Mexico in the Treaty of Guadalupe Hidalgo in eighteen forty-eight, did not have them. The terrain south of it did. So the United States bought the south.

Santa Anna needed cash, his government was nearly bankrupt, and sold. The deal was ratified by the U.S. Senate in April of eighteen fifty-four.

The Gadsden Purchase completed the contiguous territory of the lower forty-eight states. It also cut directly through the Tohono O'odham and Apache homelands without any consultation with the people living there. The line drawn in eighteen fifty-four has shaped everything since: which towns are American and which are Mexican, where the border wall runs today, which families live on which side of an international boundary that arrived one morning and divided the land where their grandparents were born.

The railroad that justified the purchase was eventually built, the Southern Pacific reached Tucson in eighteen eighty, but it was not the only thing the purchase set in motion. It also opened the southern Arizona mines. And that would define the state for the next hundred years.