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San Juan County, New Mexico facts for kids

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San Juan County
San Juan County Administration Building in Aztec
San Juan County Administration Building in Aztec
Official seal of San Juan County
Map of New Mexico highlighting San Juan County
Location within the U.S. state of New Mexico
Map of the United States highlighting New Mexico
New Mexico's location within the U.S.
Country  United States
State  New Mexico
Founded February 24, 1887
Named for San Juan River
Seat Aztec
Largest city Farmington
 • Total 5,538 sq mi (14,340 km2)
 • Land 5,513 sq mi (14,280 km2)
 • Water 25 sq mi (60 km2)  0.5%%
 • Total 121,661
 • Density 24/sq mi (9/km2)
Time zone UTC−7 (Mountain)
 • Summer (DST) UTC−6 (MDT)
Congressional district 3rd
Four Corners marker, southwestern United States
San Juan County includes the New Mexico section of the Four Corners Monument.

San Juan County is located in the U.S. state of New Mexico. As of the 2020 census, the population was 121,661 making it the fifth-most populous county in New Mexico. Its county seat is Aztec. The county was created in 1887.

San Juan County is part of the Farmington, New Mexico, Metropolitan Statistical Area. It is in the state's northwest corner and includes the New Mexico portion of the Four Corners.


According to the U.S. Census Bureau, the county has a total area of 5,538 square miles (14,340 km2), of which 5,513 square miles (14,280 km2) is land and 25 square miles (65 km2) (0.5%) is water. Indian reservations (and off-reservation trust lands) comprise 63.4 percent of the county's land area: The Navajo Indian Reservation takes up 60.45% and the Ute Mountain Ute Tribe Reservation another 2.93%.

The physical features include three rivers: the San Juan, Animas, and La Plata rivers; also, the Chuska Mountains and Shiprock Pinnacle to the west, volcanic structures, buttes, mesas, badlands, and fertile river valleys.

Adjacent counties

San Juan County in New Mexico and Utah are two of twenty-two counties or parishes in the United States with the same name to border each other across state lines. The others are Union Parish, Louisiana and Union County, Arkansas, Big Horn County, Montana and Big Horn County, Wyoming, Sabine County, Texas and Sabine Parish, Louisiana, Bristol County, Massachusetts and Bristol County, Rhode Island, Kent County, Delaware and Kent County, Maryland, Escambia County, Alabama and Escambia County, Florida., Pike County, Illinois and Pike County, Missouri, Teton County, Idaho and Teton County, Wyoming, Park County, Montana and Park County, Wyoming, and Vermilion County, Illinois and Vermillion County, Indiana. respectively. (Note, despite the different spellings, the source of the name is the same for Vermilion County, Illinois and Vermillion County, Indiana—the Vermillion River which flows through both counties.)

National protected areas

Major highways

  • US 64.svg U.S. Route 64
  • US 491.svg U.S. Route 491 (formerly U.S. Route 666)
  • US 550.svg U.S. Route 550
  • New Mexico 371.svg New Mexico State Road 371
  • New Mexico 516.svg New Mexico State Road 516
  • New Mexico 597.svg New Mexico State Road 597


Historical population
Census Pop.
1910 8,504
1920 8,333 −2.0%
1930 14,701 76.4%
1940 17,115 16.4%
1950 18,292 6.9%
1960 53,306 191.4%
1970 52,517 −1.5%
1980 81,433 55.1%
1990 91,605 12.5%
2000 113,801 24.2%
2010 130,044 14.3%
2020 121,661 −6.4%
U.S. Decennial Census
1790-1960 1900-1990
1990-2000 2010-2016

2010 census

As of the 2010 census, there were 130,044 people, 44,404 households, and 32,457 families living in the county. The population density was 23.6 inhabitants per square mile (9.1/km2). There were 49,341 housing units at an average density of 8.9 per square mile (3.4/km2). The racial makeup of the county was 51.6% white, 36.6% American Indian, 0.6% black or African American, 0.4% Asian, 0.1% Pacific islander, 7.3% from other races, and 3.5% from two or more races. Those of Hispanic or Latino origin made up 19.1% of the population. The largest ancestry groups were:

  • 34.8% Navajo
  • 15.0% English
  • 10.7% Mexican
  • 9.1% German
  • 5.9% Irish
  • 4.4% Spanish
  • 2.8% American
  • 1.8% French
  • 1.4% Italian
  • 1.2% Scottish
  • 1.1% Scotch-Irish
  • 1.1% Swedish

Of the 44,404 households, 40.5% had children under the age of 18 living with them, 49.7% were married couples living together, 15.6% had a female householder with no husband present, 26.9% were non-families, and 21.9% of households were made up of individuals. The average household size was 2.89 and the average family size was 3.38. The median age was 33.0 years.

The median household income was $46,189 and the median family income was $53,540. Males had a median income of $44,984 versus $30,245 for females. The per capita income for the county was $20,725. About 15.9% of families and 20.8% of the population were below the poverty line, including 28.0% of those under age 18 and 19.1% of those age 65 or over.



Census-designated places

Other communities

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