MSA - 4,026,135
[2]The Inland Empire is a region in Southern California mainly located in Riverside and San Bernardino Counties in the United States. The Inland Empire is centered on the oldest cities in the region Ontario, San Bernardino, and Riverside. These cities were established at about the end of the 19th century and were major centers of agriculture including citrus, dairy, and wine-making. The name "Inland Empire" was first used in the 1950s to distinguish the region from other communities of the Greater Los Angeles Area, and Los Angeles itself.
The "Inland" part of the name is derived from the region's location about 37&_160;miles (60&_160;km) inland from the Pacific Ocean (from Huntington Beach) and east of downtown Los Angeles. The most accepted physical boundary between Los Angeles, Orange County, San Diego and the Inland Empire is the definition of the Inland Empire consisting of two counties Riverside and San Bernardino county. Between the Los Angeles area and the Inland Empire there was limited development and so, until about the 1970s, this relatively open, rural space between two 'developed' regions served as a convenient boundary. However, since then rapidly growing population and, therefore, residential, commercial, and industrial development, has led to cities being established in this rural, 'intermediate' area. Interconnectivity provided by a vast automobile-oriented transportation network, including one of the most comprehensive freeway systems in the United States, has further eroded any real or perceived boundary. So the best boundary might simply be considered to be the county line that separates Los Angeles County and San Bernardino/Riverside Counties. Cities in southeastern Los Angeles County lying east of the San Jose Hills, such as Pomona, Diamond Bar, La Verne, and Claremont, are usually included. Also, the vegetation and climate changes from the coastal to desert regions can act as boundary, though a less precisely defined one than the county lines. Towards inland the climate gets colder in the winter and hotter in the summer.
More recently, the name has also been used to distinguish the area from the coastal communities of Orange County which are located to the west of the Inland Empire and south of Los Angeles County. However, because of the Santa Ana Mountains, the boundary between Orange County and the Inland Empire is more clear and obvious.
