Monticello ( MON-tih-SEL-oh) is a city in Piatt County, Illinois, United States. The population was 5,548 at the 2010 census, and 5,575 at a 2018 estimate. It is the county seat of Piatt County.Monticello is located at 40°1′41″N 88°34′23″W (40.028092, −88.573003).According to the 2010 census, Monticello has a total area of 3.829 square miles (9.92 km2), of which 3.8 square miles (9.84 km2) (or 99.24%) is land and 0.029 square miles (0.08 km2) (or 0.76%) is water.Monticello is located in East Central Illinois between the cities of Decatur and Champaign, Illinois.Monticello is nearly equidistant from Chicago, St. Louis, and Indianapolis.
Monticello’s first non-native resident was George Haworth. Haworth came to the area in 1822 to serve as a U.S. liaison agent to local Native American tribes. Haworth did not remain, but in 1829, James A. Piatt purchased Haworth’s small log cabin. Soon more settlers arrived. In 1837, residents decided to form a new town. Abraham Marquiss, William Barnes, James McReynolds, and James A. Piatt Jr. formed a joint stock company and purchased land from James A. Piatt. Upon McReynolds’ suggestion, the town was christened Monticello – after the home of Thomas Jefferson. Monticello officially became a town on July 1, 1837. Townsfolk held a celebration on July 4.
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