The American Conquest, Eighteen Forty-Six

On August eighteenth, eighteen forty-six, General Stephen Watts Kearny rode into Santa Fe at the head of the Army of the West and raised the American flag over the Palace of the Governors. New Mexico had been Mexican territory for twenty-five years. Before that it had been Spanish for two centuries.

Now, in a single afternoon, it changed hands again, and this time, it stayed changed. The Mexican-American War had begun in May, after fighting broke out in disputed territory along the Rio Grande. New Mexico was only one theater among many, but Kearny understood its symbolic importance.

He entered the province through the Raton Pass, received the surrender of Governor Manuel Armijo, who may have been bribed to stand down, and proclaimed American sovereignty over a population of roughly sixty thousand people, the vast majority of them Hispanic and Pueblo Indian, none of whom had been consulted. The Treaty of Guadalupe Hidalgo, signed February second, eighteen forty-eight, formally ended the war and transferred New Mexico along with California and present-day Arizona to the United States. Under the treaty, Mexican citizens who remained in the ceded territories would automatically become American citizens and their property rights would be respected.

That second promise proved harder to keep than the first. New Mexico became a formal territory in eighteen fifty, under the Compromise of that year. It would remain a territory for sixty-two years, longer than any other contiguous United States territory, a delay partly attributable to Congress's reluctance to admit a territory whose population was predominantly Catholic, Spanish-speaking, and of mixed ancestry.

Statehood finally came on January sixth, nineteen twelve, making New Mexico the forty-seventh state. Arizona followed six weeks later, the last of the lower forty-eight.