San Luis Río Colorado is a municipality in the state of Sonora in northwestern Mexico, being the northwesternmost municipality in Sonora and covering an area of 8412.75 km2.

[1][2] The municipality is the location of the city of San Luis Rio Colorado (its municipal seat), the community of El Golfo de Santa Clara, and the Bahia Adair biosphere preserve.

The municipality is in the Lower Colorado River Valley, with the Colorado River along its west, the U.S.-Mexico border along the north, and to the Colorado River Delta on the southwest, and the Gulf of California (Sea of Cortez) along the south.

The largest cities, towns, and villages within the municipality include: Former historical settlements sites within the current municipality, many along the Colorado River that served shipping by steamboats on the Colorado River, include: The first vaccines against the COVID-19 pandemic in Mexico arrived for medical personal on January 13, 2021.

[3] Eleven people were arrested for possession of weapons reserved for the military on March 13, 2021.