History and Facts of New Mexico Counties

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Territory: Sep 9, 1850
Statehood: Jan 6, 1912
Counties: 33
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.

Table of Contents hide

1 New Mexico Territorial Counties

2 New Mexico Counties Today

3 Fun Facts about New Mexico Counties

3.1 Counties by Year

3.2 County Size Facts

3.3 County Population Facts

3.4 New Mexico City Facts

4 Boundary Changes of New Mexico Counties from 1845-1981

5 List of New Mexico Counties

6 List of Old Former / Extinct New Mexico Counties

6.1 Santa Ana County, New Mexico

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

Today, New Mexico is divided into 33 counties. States bordering New Mexico are Arizona, Colorado, Oklahoma, Texas and Utah.

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
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.