Rio Arriba County comprises the Española, NM Micropolitan Statistical Area, which is also included in the Albuquerque-Santa Fe-Las Vegas, NM Combined Statistical Area.

Originally extending west to the California line, it included the site of present-day Las Vegas, Nevada.

[3] The county seat was initially sited at San Pedro de Chamita, and shortly afterwards at Los Luceros.

[4] The Battle of Embudo Pass took place in the southern part of the county during the Mexican–American War in January 1847.

The highest point in the county is the summit of Truchas Peak at 13,102 feet (3,993 m).

23.50% of all households were made up of individuals, and 7.80% had someone living alone who was 65 years of age or older.

[15] From New Mexico's statehood to the early 1930s Rio Arriba was a traditional Republican county.

The last Republican presidential candidate to carry the county was Dwight D. Eisenhower in 1956.

[17] It is located in New Mexico's 3rd congressional district, which has a Cook Partisan Voting Index rating of D+7 and is represented by Democrat Teresa Leger Fernandez.

[19] Current commissioners are: Rio Arriba County has six public school districts.