Peoria (/piːɔəriə/) is the largest city on the Illinois River and the county seat of Peoria County, Illinois, in the United States. It is named after the Peoria tribe. As of the 2010 census, the city was the seventh-most populated in Illinois, with a population of 115,007, and is the third-most populated metropolitan area in Illinois outside of the Chicago Metropolitan Area. The Peoria Metropolitan Statistical Area had a population of 372,487 in 2008, making it the third largest metropolitan area in the state after the Chicago metropolitan area and the Metro-East portion of the St. Louis metropolitan area.
Peoria has become famous as a representation of the average American city because of its demographics and its perceived mainstream Midwestern culture. On the Vaudeville circuit, it was said that if an act would succeed in Peoria, it would work anywhere. The question "Will it play in Peoria?" has now become a metaphor for whether something appeals to the American mainstream public.
Peoria is the home of Ray LaHood, now serving as Secretary of Transportation in President Obama's cabinet. It is also headquarters for Caterpillar Inc., one of the 30 companies composing the Dow Jones Industrial Average.