San Juan County is a county located in the U.S. state of New Mexico. It is part of the Farmington, New Mexico Metropolitan Statistical Area. As of 2000, the population was 113,801. Its county seat is Aztec.
The physical features include three rivers, the San Juan, Animas and the La Plata, volcanic structures, buttes, mesas, badlands, and fertile river valleys.
There were 37,711 households out of which 42.00% had children under the age of 18 living with them, 55.70% were married couples living together, 14.70% had a female householder with no husband present, and 23.30% were non-families. 19.30% of all households were made up of individuals and 6.40% had someone living alone who was 65 years of age or older. The average household size was 2.99 and the average family size was 3.43.
In the county the population was spread out with 32.60% under the age of 18, 10.00% from 18 to 24, 28.10% from 25 to 44, 20.20% from 45 to 64, and 9.10% who were 65 years of age or older. The median age was 31 years. For every 100 females there were 98.30 males. For every 100 females age 18 and over, there were 94.70 males.
The median income for a household in the county was $33,762, and the median income for a family was $37,382. Males had a median income of $35,066 versus $21,299 for females. The per capita income for the county was $14,282. About 18.00% of families and 21.50% of the population were below the poverty line, including 26.60% of those under age 18 and 18.20% of those age 65 or over.