The Inland Empire – locally known as the I.E. – is a metropolitan area and region of Southern California. It is situated directly east of the Los Angeles metropolitan area. The term "Inland Empire" is most commonly used in reference to the U.S. Census Bureau's federally defined Riverside-San Bernardino-Ontario metropolitan area, which covers more than 27,000 square miles (70,000 km2). The metropolitan area consists of Riverside County and San Bernardino County (and for a more strict definition, only the urbanized and built up areas of these two counties immediately east of the Los Angeles metropolitan area). According to the U.S. Census, the counties of San Bernardino and Riverside are home to over 4 million people and is the 12th most populous metropolitan area in the United States, and the third most populous in the state of California. Most of the area's population is located in the southwest corner of the region. At the end of the 19th century, the Inland Empire was a major center of agriculture, including citrus, dairy, and wine-making. Agriculture declined through the 20th century, and since the 1970s a rapidly growing population, fed by families migrating in search of affordable housing, has led to more residential, industrial, and commercial development. The U.S. Census Bureau also combines the Los Angeles metropolitan area and the Inland Empire into one larger region known as the Greater Los Angeles Area with a population of over 17 million.

en.wikipedia.org/wiki/Inland_Empire_(California)