New Mexico County Map: All 33 Counties

Under the Treaty of Guadalupe Hidalgo of 1848, the United States agreed to protect existing property titles and community land grants (mercedes) established during Spanish and Mexican rule. Today, communal grazing and timber rights in northern counties (Rio Arriba, Taos, San Miguel, Mora) continue to interact with county tax and zoning laws.

Furthermore, traditional community irrigation ditch associations—acequias—are recognized under Section 73-2-1 of the New Mexico Statutes as political subdivisions of the state, possessing powers independent of county commissions to regulate surface water allocations from the Rio Grande and Rio Chama.

Alongside 19 sovereign Native American Pueblos, the Jicarilla and Mescalero Apache reservations, and the Navajo Nation, New Mexico county sheriffs and commissioners coordinate multi-jurisdictional law enforcement and infrastructure agreements across reservation borders.

Catron County in southwestern New Mexico spans 6,924 square miles—larger than four different Eastern states. Containing the heart of the Gila Wilderness (the world's first designated wilderness area created in 1924) and the Mogollon Mountains, Catron County is home to just over 3,500 residents, meaning there are nearly two square miles of land per person.

At the opposite end of the spectrum is Los Alamos County. Covering just 109 square miles in the Jemez Mountains, it was created during the Manhattan Project as a secret atomic research site. Today, operating as a consolidated city-county, Los Alamos boasts the highest percentage of doctorate holders and the highest median household income in New Mexico.

Bernalillo County anchors the central Rio Grande corridor, where the City of Albuquerque, Sandia National Laboratories, and Kirtland Air Force Base drive the economic life of over 675,000 New Mexicans.