New Mexico Territory

Territory of New Mexico
Organized incorporated territory of the United States





FlagCoat of arms
FlagCoat of arms
Location of New Mexico Territory
A map of the later Federal Arizona and New Mexico Territories, split from the original New Mexico Territory of 1851, showing existing counties.
CapitalSanta Fe
GovernmentOrganized incorporated territory
 • 1851–1852James S. Calhoun
 • 1910–1912William J. Mills
LegislatureNew Mexico Territorial Legislature
 • Treaty of Guadalupe HidalgoMay 30, 1848
 • Organic Act (part of Compromise of 1850)September 9, 1850
 • Gadsden PurchaseJune 24, 1853
 • Colorado Territory establishedFebruary 28, 1861
 • Arizona Territory establishedFebruary 24, 1863
 • StatehoodJanuary 6, 1912

The Territory of New Mexico was an organized incorporated territory of the United States that existed (with varying boundaries) from September 9, 1850, until January 6, 1912, when the remaining extent of the territory was admitted to the Union as the State of New Mexico, making it the longest-lived organized incorporated territory of the United States, lasting approximately 62 years.

Before the Territory was organized

Proposed boundaries for the earlier federal State of New Mexico, 1850

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

Earlier in the year 1850, a bid for New Mexico statehood was underway under a proposed state constitution prohibiting 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. Texas raised great opposition to 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.