
Map of Arizona and New Mexico Territories
The 'New Mexico Territory' became an
organized territory of the
United States on
September 9,
1850, and it existed until
New Mexico became the 47th
state on
January 6,
1912.
The western portion of New Mexico came from the
Treaty of Guadalupe Hidalgo in 1848, while the remainder of eastern New Mexico (from the
Rio Grande to the present New Mexico-
Texas border) was added as consequence of the
Compromise of 1850. The
Gadsden Purchase of 1853 added a smaller additional area to New Mexico Territory—the southernmost strip of Arizona and New Mexico.
The land contained in the original 1850 New Mexico Territory was the western portion of the future state, plus most of future
Arizona (known as
Santa Ana County), a small part of
Colorado, and
Nevada south of
36° 30' N. The Texan cession and the Gadsden Purchase expanded the territory greatly, but the establishment of
Colorado Territory on
February 28,
1861 and of
Arizona Territory on
February 24,
1863 (west of the 109th
meridian) left New Mexico with its present boundaries.
As the route to
California, New Mexico and Arizona were disputed territory during the
American Civil War, resulting in Gadsden settlers willingly joining the
Confederate States of America. The
"Gettysburg of the West" gave the area primarily to the
Union at the
Battle of Glorieta Pass.
Confederate Arizona Territory was the first American incarnation of
Arizona.
See also

New Mexico Territory 1866
★
Governors of New Mexico Territory
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Historic regions of the United States
★
Santa Fe de Nuevo México
★
History of New Mexico
★
Arizona Territory was created from parts of the former New Mexico Territory, so histories overlap