New Mexico Territory

The Territory of New Mexico was an organized incorporated territory of the United States from September 9, 1850, until January 6, 1912. It was created from the U.S. provisional government of New Mexico, as a result of Nuevo México becoming part of the American frontier after the Treaty of Guadalupe Hidalgo. It existed with varying boundaries until the territory was admitted to the Union as the U.S. state of New Mexico in 1912. This jurisdiction was an organized, incorporated territory of the US for nearly 62 years, the longest period of any territory in the contiguous United States.

In 1846, during the Mexican–American War, the United States established a provisional government of New Mexico. Territorial boundaries were somewhat ambiguous. After the Mexican Republic formally ceded the region to the United States in 1848, this temporary wartime/military government operated until September 9, 1850.

Earlier in 1850, organizers proposing New Mexico for statehood had drafted a state constitution that prohibited slavery. The request was approved at the same time that the Utah Territory was created to the north. The proposed state boundaries were to extend as far east as the 100th meridian West and as far north as the Arkansas River, thus encompassing the present-day Texas and Oklahoma panhandles and parts of present-day Kansas, Colorado, Utah, and Arizona, as well as most of present-day New Mexico. The state of Texas (admitted to the US in 1845) strongly criticized this plan, as it claimed much of the same territory, although it did not control these lands. In addition, slaveholders worried about not being able to expand slavery to the west of their current slave states.

The Compromise of 1850 put an end to the push for immediate New Mexico statehood. Approved by the United States Congress in September 1850, the legislation provided for the establishment of New Mexico Territory and Utah Territory. It also defined the disputed western boundary of Texas.

During the territorial period, the status of slavery provoked considerable debate. Congress was sharply divided on the slavery issue, with Southern representatives determined to protect their options for expansion of slavery in the West. Senator Stephen A. Douglas of Illinois and others maintained that the territory could not restrict slavery, as under the earlier Missouri Compromise. Others, including Abraham Lincoln, insisted that older Mexican Republic legal traditions of the territory, which abolished black slavery in 1834, took precedence and should be continued. (Indian slavery had been abolished in Spanish colonies in 1769.) Regardless of the official status, slavery was rare in antebellum New Mexico. Black slaves never numbered more than about a dozen.

As one of the final attempts at compromise to avoid the Civil War, in December 1860, a U.S. House of Representatives committee proposed to admit New Mexico as a slave state immediately. Although the measure was approved by the committee on December 29, 1860, Southern representatives did not take up this offer. Many had already left Congress due to the imminent declarations of secession by their states.

On February 24, 1863, during the Civil War, Congress passed the "Arizona Organic Act", which split off the western portion of the 12-year-old New Mexico Territory, establishing the new Arizona Territory, where it abolished slavery. As in New Mexico, slavery was already extremely limited, due to earlier Mexican traditions, laws, and patterns of settlement. The northwestern corner of New Mexico Territory was included in Arizona Territory until it was added to the southernmost part of the newly admitted State of Nevada in 1864. Eventually, Arizona Territory was admitted in 1912 as the State of Arizona.

The boundaries of the New Mexico Territory at the time of establishment (September 9, 1850) contained most of the present-day State of New Mexico, more than half of the present-day State of Arizona, and portions of the present-day states of Colorado and Nevada. Although this area was smaller than what had been included in the failed statehood proposal of early 1850, the boundary disputes with Texas had been dispelled by the Compromise of 1850.