Peoria is the largest city on the Illinois River and is the county seat of Peoria County Illinois. As of the 2010 census, the Peoria Metropolitan Area has a population of over 372,000, and is the third largest metropolitan area in the state after the Chicago metro area and the Metro-East portion of St. Louis.

Peoria has become famous as a representation of the average American city because of its demographics and its 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 become a metaphor for whether something appeals to the American mainstream public.

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There are three hospitals in Peoria; OSF Saint Francis Medical Center, Methodist Medical Center and Proctor Hospital.

OSF Saint Francis Medical Center, which is the largest hospital in the Peoria metropolitan area, is the Level 1 adult and pediatric regional trauma center for a 26 county region in central Illinois. The Center is home to the Children's Hospital of Illinois, the midwest affiliate of St. Jude's Children's Research Hospital, and the OSF Saint Francis Heart Hospital. OSF Saint Francis Medical Center is a teaching hospital for the University of Illinois College of Medicine at Peoria, and trains nearly 200 residents and fellows in eleven fields.