Blythe is a city in Riverside County, California, United States, in the Palo Verde Valley of the Lower Colorado River Valley region, an agricultural area and part of the Colorado Desert along the Colorado River. Blythe was named after Thomas H. Blythe, a San Francisco financier, who established primary water rights to the Colorado River in the region in 1877. The city was incorporated on July 21, 1916. The population was 20,817 at the 2010 census.