Peoria is a city in and the
county seat of
Peoria County,
Illinois,
United States, and the largest city on the
Illinois River. Established in 1691 by the French explorer
Henri de Tonti, Peoria is the oldest European settlement in Illinois, and is named after the
Peoria tribe. As of the
2010 census, the city was the seventh-most populated in Illinois (and the third largest outside of
Chicagoland), with a population of 115,007. The Peoria
Metropolitan Statistical Area had a population of 373,590 in 2011. Peoria had a population of 118,943 in 2010, when far northern Peoria was also included. Peoria is the headquarters for
Caterpillar Inc., one of the 30 companies composing the
Dow Jones Industrial Average.