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

Today, New Mexico is divided into 33 counties.  States bordering New Mexico are ArizonaColoradoOklahomaTexas 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

County Population Facts

New Mexico City Facts

New Mexico’s 10  largest cities (2016 est.) are:

  1. Albuquerque (545,852) is in Bernalillo County
  2. Las Cruces (97,618) is in Doña Ana County
  3. Rio Rancho (87,521) is in Bernalillo County and Sandoval County
  4. Santa Fe (67,947) is in Santa Fe County
  5. Roswell (48,366) is in Chaves County
  6. Farmington (45,877) is in San Juan County
  7. Clovis (37,775) is in Curry County
  8. Hobbs (34,122) is in Lea County
  9. Alamogordo (30,403) is in Otero County
  10. 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

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.

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