Formed January 1, 1841 (91st county)
Piatt County (16,672), Monticello (5,941)
A red brick and masonry courthouse for Piatt County was built in 1903 in Second Empire style. It is sited on a square at Washington, Charter, Main, and State streets. Illinois State Highway 105 is one block west of the location. Joseph W. Royer is the building designer. The building features a hidden dome and memorial walls are on the grounds. Macon and De Witt counties provided the land for Piatt County on January 1, 1841 as the 91st county with Monticello as the only county seat. Settler James A. Piatt is the namesake for the county. The county seat is named after the estate of President Thomas Jefferson.
Piatt County government consists of a sheriff, an attorney, a coroner, a clerk, a treasurer, and an assessor (executive). It has 8 Board Members (legislative.) Eleven Circuit Court Judges serve Piatt, Champaign, DeWitt, Douglas, Macon, and Moultrie counties and a court clerk serves Piatt County (judicial.) The county is in east central Illinois. Springfield, Illinois is west and Champaign, Illinois is immediately east of the county. The county center is 2.1 miles North of Monticello. The county is surrounded clockwise by McLean, Champaign, Douglas, Moultrie, Macon, and De Witt counties.
The area of the county is 439 square miles. It is 64 out of 102 in the state. It ranks 65 out of 102 in population in the state. It has a density of 38.0 persons per square mile making it 65 out of 102 in the state. Piatt County has 68.8% of its population in its incorporated areas. Interstate Highway 72 crosses the county from east to southwest from Champaign County to Macon County. Interstate Highway 74 goes through the northern top of the county from Champaign County, east, to De Witt County, west. United States Highway 150 parallels Interstate Highway 74 from Champaign to De Witt counties. The county is a tall rectangle with its northwest corner missing. Monticello is slightly south of center in the county. Monticello is the county seat and the largest city. It is 35.6% of the county population. This county is in the Champaign-Urbana Metropolitan Statistical Area.
Bement
Cerro Gordo
Cisco
De Land
Hammond
Mansfield
Monticello
Atwood
Ivesdale