The Inland Empire is a metropolitan area or region inland of and adjacent to coastal Southern California, centering around the cities of San Bernardino and Riverside, and bordering Los Angeles County to the east. The bulk of the population is centered in the cities of northwestern Riverside County and southwestern San Bernardino County, and is sometimes considered to include the desert communities of the Coachella and Victor Valleys, respectively on the other sides of the San Gorgonio Pass and San Bernardino Mountains from the Santa Ana River watershed that forms the bulk of the Inland Empire; a much broader definition includes all of Riverside and San Bernardino counties. The combined land area of the counties of the Inland Empire is larger than ten U.S. states—West Virginia, Maryland, Hawaii, Massachusetts, Vermont, New Hampshire, New Jersey, Connecticut, Delaware and Rhode Island.

Southern California is a geographic and cultural region that generally comprises the southern portion of the U.S. state of California. It includes the Los Angeles metropolitan area as well as the Inland Empire. The region generally contains ten of California's 58 counties: Imperial, Kern, Los Angeles, Orange, Riverside, San Bernardino, San Diego, Santa Barbara, San Luis Obispo and Ventura counties.