Blythe is a city in Riverside County, California, United States, in the Colorado River Valley (in California, the "Palo Verde Valley"), an agricultural area along the Colorado River. Blythe was named after Thomas Blythe, a gold prospector 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 12,155 at the 2000 census.