Imperial is a county outside of Southern California.
El Centro is a city in and county seat of Imperial County , California , the largest city in the Imperial Valley , east anchor of the Southern California Border Region , and the core urban area and principal city of the El Centro metropolitan area which encompasses all of Imperial County . Southern California . The region is traditionally described as eight counties , based on demographics and economic ties : Imperial , Los Angeles , Orange , Riverside , San Bernardino , San Diego , Santa Barbara , and Ventura .