The Gadsden Purchase, 1853–1854: How the U.S.–Mexico Border Was Drawn

The land bought in the Gadsden Purchase. Image from the Office of the Historian, U.S. Department of State.

The Gadsden Purchase, or Gadsden Treaty, finalized in 1854, was an agreement in which the United States paid Mexico $10 million for 29,670 square miles of Mexican territory that later became part of Arizona and New Mexico. It gave the United States the land it needed for a southern transcontinental railroad, and was meant to settle disputes left over from the Mexican-American War.

Unfinished business

The Treaty of Guadalupe Hidalgo formally ended the Mexican-American War in February 1848, but tensions simmered for six more years. Both countries claimed the Mesilla Valley. Mexico demanded compensation for Native American raids, since the United States had promised in the treaty to protect Mexico from them; the United States replied that it had agreed to protect, not to pay for raids that happened. Private Americans who crossed illegally into Mexico to stir up rebellions and grab land made things worse.

The tension also blocked the search for a southern railroad route: the only practical routes ran through Mexican territory. In 1847 the United States had tried to buy the Isthmus of Tehuantepec as a southern link between the Atlantic and Pacific. But Mexico had already granted José de Garay the right to found colonies there for Americans, financed from New Orleans; fearing the colonists would rebel as Texas had, a Mexican president revoked the grant, angering American investors.

Gadsden's mission

In 1853 Mexican officials evicted Americans from their land in the Mesilla Valley, and New Mexico's governor, William Lane, declared the valley part of U.S. territory. President Antonio de Santa Anna sent troops. To defuse the crisis, President Franklin Pierce sent James Gadsden, the new U.S. minister to Mexico, with instructions from Secretary of State William Marcy: secure a border that allowed a southern railroad, end U.S. obligations over the Native American raids, and settle the claims over the Garay project.

Mexican President Antonio de Santa Anna. Image from the Office of the Historian, U.S. Department of State.

Gadsden met Santa Anna on September 25, 1853. Pierce's verbal instructions, carried by Christopher Ward, an agent of the Garay project's American investors, offered options from $50 million for Lower California and much of northern Mexico down to $15 million for a smaller strip. Ward also falsely told Gadsden that the President wanted the Garay claims settled in any treaty; Pierce, who opposed government involvement in private companies' dealings with foreign governments, had said no such thing.

Santa Anna would not sell a large part of Mexico, but he needed money for an army to put down rebellions. On December 30, 1853, he and Gadsden signed a treaty: $15 million for 45,000 square miles.

A smaller deal

Amid growing strife between North and South, the U.S. Senate ratified a revised treaty only with great difficulty, on April 25, 1854. It cut the price to $10 million and the land to 29,670 square miles, and dropped any mention of the raids and the private claims. Pierce signed it, and Santa Anna signed on June 8, 1854.

The purchase did not end the quarrels: a new border dispute arose over the payment, and the claims and border raids stayed unresolved. But it drew the southern border of today's United States — even though most policymakers of the time expected the country to keep expanding into Mexico.

Sources

• U.S. Department of State, Office of the Historian, "Gadsden Purchase, 1853–1854," Milestones in the History of U.S. Foreign Relations, dedicated to the public domain under CC0; rewritten in hubnx's own words.