Tazewell County is a county in the U.S. state of Illinois. According to the 2020 census, it had a population of 131,343. Its county seat and largest city is Pekin. It is pronounced with a short "a", to rhyme with "razz" rather than "raze."

The Peoria Metropolitan Statistical Area, as defined by the United States Census Bureau, is an area consisting of six counties in Central Illinois, anchored by the city of Peoria. As of the 2020 census, the area had a population of 402,391. The City of Peoria, according to the 2020 US Census Bureau, has 113,150 people.