Events always have a precursor and the Gadsden Purchase is no exception. The Treaty of Guadalupe Hidalgo, signed on February 2, 1848, ended the war with Mexico. It confirmed U.S. claims to Texas and set its boundary at the Rio Grande. Mexico also agreed to cede to the United States, California and New Mexico. This included what is now California, Arizona, Nevada and Utah as well as parts of New Mexico, Colorado and Wyoming. The purchase price was $15 million and assumption by the United States of claims against Mexico by U. S. citizens. The U. S. Senate ratified it on March 10, 1848 and the Mexican Congress on May 25.
The boundary was vague and both sides were unhappy. Mesilla was a part of Mexico and was on the west bank of the Rio Grande. Las Cruces and Dona Ana were on the east bank of the river and were in American territory. So many pioneers came to claim the American land, many native Mexicans moved away. If they wanted to remain in the area they just moved across the river. The town of Chamberino began as a refuge for New Mexicans who could choose between Mexico and the United States. In 1853 the Mesilla Civil Colony Land Grant was issued by the Mexican government, and Mesilla was formed. President Franklin Pierce wanted to insure U. S. possession of the Mesilla Valley as it was the most practical route for a southern railroad to the Pacific, but it was still owned by Mexico.
Enter James Gadsden, railroad promoter and diplomat. Gadsden was appointed Minister to Mexico in 1853 and was instructed to purchase the border strip of approximately 30,000 square miles. The purchase would include the Mesilla Valley, providing the land for the southern railroad. Gadsden negotiated the purchase for $10 million, and the Senate ratified it in 1854 by a narrow margin. Those who had moved across the river to be in Mexico now found themselves in the United States. The U. S. Government, however, honored the ownership under the Mexican Land Grant. On November 16, 1854 the flag of Mexico was lowered and the flag of the United States was raised in the plaza of Mesilla. Unfortunately the Santa Fe Railroad did not include Mesilla in its railroad route but chose Las Cruces instead.
There is a Gadsden Museum just off the main plaza in Mesilla, a tribute to the man who helped change the course of New Mexico’s history.