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.

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

While Donald Trump still lost the county by almost 20 points, his performance was the best by a Republican since Nixon's landslide in 1972.

In this election the Tierra Amarilla and Chama corridor flipped to a Republican majority.

Española also saw a heavy Republican trend, as did all other major population centers in the county.

Rio Arriba showed, along with McKinley, Mora, Guadalupe Counties, the strongest Republican shift in the state of New Mexico in 2024.

[18] 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.

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