|NM State Facts|
|Territory: Sep 9, 1850|
|Statehood: Jan 6, 1912|
|Borders: AZ, CO, OK, TX and UT|
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Today’s New Mexico counties did not always exist in the present form. They went through many different changes in the space of a few short years.
New Mexico Territorial Counties
The New Mexico Territory was organized as territory on September 9, 1850. There were originally nine counties formed in 1852. Santa Ana County, New Mexico Territory, one of the nine original counties, was annexed in 1876 to Bernalillo County, New Mexico.
The State of New Mexico entered the union as the 47th state on January 6, 1912.
New Mexico Counties Today
Fun Facts about New Mexico Counties
Counties by Year
- Socorro, San Miguel, Taos, Rio Arriba, Valencia, Santa Fe, Doña Ana and Bernalillo Counties was the original 9 counties created in 1852.
- Cibola County was the last county created on 1981.
County Size Facts
- Catron County (6,928 sq mi) is the largest county in New Mexico.
- Los Alamos County (109 sq mi) is the smallest county in New Mexico.
County Population Facts
- Harding County (740) is the least populated county in New Mexico.
- Bernalillo County (670,968) is the most populated county in New Mexico.
New Mexico City Facts
New Mexico’s 10 largest cities (2016 est.) are:
- Albuquerque (545,852) is in Bernalillo County
- Las Cruces (97,618) is in Doña Ana County
- Rio Rancho (87,521) is in Bernalillo County and Sandoval County
- Santa Fe (67,947) is in Santa Fe County
- Roswell (48,366) is in Chaves County
- Farmington (45,877) is in San Juan County
- Clovis (37,775) is in Curry County
- Hobbs (34,122) is in Lea County
- Alamogordo (30,403) is in Otero County
- Carlsbad (26,138) is in Eddy County
Boundary Changes of New Mexico Counties from 1845-1981
This Interactive Map of New Mexico Counties show the historical boundaries, names, organization, and attachments of every county, extinct county and unsuccessful county proposal from 1845 to 1981.
List of New Mexico Counties
|County||Created||Created From||Named For||County Seat||Disbanded / Renamed||Notes|
|Bernalillo County||06 Jan 1852||One of the nine original counties||In honor of Gonzales-Bernal family; Spanish nobles who settled the territory in the seventeenth century||Albuquerque|
|Bergen County||25 Feb 1921||Socorro County||In honor of Thomas Benton Catron; a Santa Fe attorney and New Mexico’s first U.S. Senator||Reserve|
|Burlington County||25 Feb 1889||Lincoln County||In honor of Jose Francisco Chaves (1833-1904); a U.S. Army colonel in New Mexico during and after the American Civil War, politician, lawyer, and rancher from the New Mexico Territory||Roswell|
|Cibola County||19 Jun 1981||Valencia County||The mythical Seven Cities of Cibola||Grants|
|Colfax County||25 Jan 1869||Mora County||In honor of Schuyler Colfax (1823-1885), the seventeenth vice president of the United States||Raton|
|Curry County||25 Feb 1909||Quay and Roosevelt Counties||In honor of George Curry, a governor of New Mexico Territory (1907-1910)||Clovis|
|De Baca County||28 Feb 1917||Chaves and Guadalupe Counties||In honor Ezequiel Cabeza de Baca (1864-1917), the second state governor of New Mexico||Fort Sumner|
|Dona Ana County||06 Jan 1852||One of the nine original counties||In honor of Doña Ana Robledo, a seventeenth century Spanish woman known for her charitable giving to the native population||Las Cruces|
|Eddy County||25 Feb 1889||Lincoln County||In honor of Charles Eddy, a rancher and developer of the area||Carlsbad|
|Grant County||30 Jan 1868||Doña Ana County||In honor of Ulysses Simpson Grant (1822-1885); commanding general of the Union Army during the American Civil War general and 18th President of the United States (1869-1877)||Silver City|
|Guadalupe County||26 Feb 1891||San Miguel County||In honor of Our Lady of Guadalupe, the patron saint of the Americas||Santa Rosa|
|Harding County||04 Mar 1921||Mora and Union Counties||In honor of Warren Gamaliel Harding (1865-1923), the 29th President of the United States (1921-1923)||Mosquero|
|Hidalgo County||25 Feb 1919||Grant County||In honor of Miguel Hidalgoy Costilla (1753-1811), the priest who is known as the “Father of Mexican Independence”||Lordsburg|
|Lea County||07 Mar 1917||Chaves and Eddy Counties||In honor of Joseph Calloway Lea, a captain in the U.S. Army and the founder of the New Mexico Military Academy||Lovington|
|Lincoln County||16 Jan 1869||Socorro County||In honor of Abraham Lincoln (1809-1865), a lawyer and the 16th president of the United States (1861-1865)||Carrizozo|
|Los Alamos County||16 Mar 1949||Sandoval and Santa Fe Counties||Its county seat of Los Alamos, New Mexico, which itself is the Spanish name for the “cottonwood tree”||Los Alamos|
|Luna County||16 Mar 1901||Doña Ana and Grant Counties||In honor of Solomon Luna, the largest land owner in the county at the time of its creation; itself Spanish for “moon”||Deming|
|McKinley County||23 Feb 1899||Bernalillo County||In honor of William McKinley (1843-1901), the 25th president of the United States (1897-1901) until his assassination six months into his second term||Gallup|
|Mora County||01 Feb 1860||Taos County||Its county seat of Mora, New Mexico, which is itself named after “lo de mora”, the Spanish term for “blackberry”||Mora|
|Otero County||30 Jan 1899||Doña Ana and Lincoln Counties||In honor of Miguel A. Otero, territorial delegate to U. S. Congress||Alamogordo|
|Quay County||28 Feb 1903||Guadalupe County||In honor of Matthew Stanley Quay, a U.S. Senator from Pennsylvania who supported New Mexico’s statehood||Tucumcari|
|Rio Arriba County||06 Jan 1852||One of the nine original counties||Its location on the upper Rio Grande. Rio Arriba is “upper river” in Spanish||Tierra Amarilla|
|Roosevelt County||28 Feb 1903||Chaves and Guadalupe Counties||In honor of Theodore “Teddy” Roosevelt (1858-1919), the 26th President of the United States (1901-1909)||Portales|
|San Juan County||24 Feb 1887||Bernalillo County||In honor of San Juan River, itself named after the Catholic saint||Bernalillo|
|San Miguel County||09 Jan 1852||Rio Arriba County||San Miguel de Bado Catholic Church, the first in the area||Aztec|
|Sandoval County||10 Mar 1903||One of the nine original counties||Sandoval family, prominent seventeenth century Spanish landowners||Las Vegas|
|Santa Fe County||06 Jan 1852||One of the nine original counties||Spanish term meaning “holy faith,” which refers to the spirituality of the founding missionaries||Santa Fe|
|Sierra County||03 Apr 1884||Doña Ana and Socorro Counties||Possibly named for the Black Range. Sierra is “mountain range” in Spanish.||Truth or Consequences|
|Socorro County||06 Jan 1852||One of the nine original counties||Spanish term meaning “aid,” which refers to the help Native Americans gave to starving travelers||Socorro|
|Taos County||06 Jan 1852||One of the nine original counties||Its county seat of Taos, New Mexico. It was named for the nearby Taos Pueblo, an ancient Native American village. Taos is “red willow” in the Tiwa language||Taos|
|Torrance County||16 Mar 1903||Bernalillo and Valencia Counties||In honor of Francis J. Torrance, the developer of the New Mexico Central Railroad||Estancia|
|Union County||23 Feb 1893||Colfax, Mora and San Miguel Counties||The “union” of the three counties which donated land to form the new county||Clayton|
|Valencia County||06 Jan 1852||One of the nine original counties||The town of Valencia, New Mexico, which is itself named for Valencia, Spain||Los Lunas|
List of Old Former / Extinct New Mexico Counties
New Mexico contains some counties that no longer exist because they were discontinued, renamed or merged with another county. These are important for genealogy research purposes.
The below counties formerly within the area of the State of New Mexico no longer exist:
Santa Ana County, New Mexico
[1852 Map] was one of the seven original partidos created in New Mexico under Mexican rule (was in Judicial District No. 1 from 1847 to 1863, then in JD 2 until 1876). Under U.S. rule, it became a U.S. Territorial county from 1852 until 1876, when it was absorbed by Bernalillo County.