[2] The county was named for Miguel Antonio Otero, one of the founders of the town of La Junta and a member of a prominent Hispanic family.

[3] At the 2000 census there were 20,311 people, 7,920 households, and 5,472 families living in the county.

The racial makeup of the county was 79.02% White, 0.76% Black or African American, 1.43% Native American, 0.70% Asian, 0.08% Pacific Islander, 15.06% from other races, and 2.96% from two or more races.

[9] Of the 7,920 households 32.20% had children under the age of 18 living with them, 52.70% were married couples living together, 12.00% had a female householder with no husband present, and 30.90% were non-families.

Before that, Otero tended to be a Republican-leaning county at the Presidential level, although it did vote for Wilson twice, FDR in 1932 and 1936, Truman in 1948 and Lyndon Johnson in 1964.