According to the 2010 census, the township has a total area of , of which (or 99.91%) is land and (or 0.09%) is water. The streams of Wildcat Creek and Willow Branch run through this township. Both streams are tributaries of the Sangamon River which runs from northeast to southwest through the township. Willow Branch is part of Townships 17 and 18 North, Range 4 and 5 East of the Third Principal Meridian.
Robert Allerton Park, owned by the University of Illinois, is located in parts of Sections 20, 21, 22, 27, 28, 29, 30; T.18 N., R.5 E.
Cities and towns •
Cisco Extinct towns • Amenia
Adjacent townships •
Goose Creek Township (north) •
Monticello Township (east) •
Bement Township (southeast) •
Cerro Gordo Township (south) •
Oakley Township, Macon County (southwest) •
Friends Creek Township, Macon County (west) •
Whitmore Township, Macon County (west) •
Nixon Township, DeWitt County (northwest)
Cemeteries The township contains eight cemeteries: Ater, Cronninger, Pioneer, Stringtown, Van Meter, Warfield Family, West France and Willow Branch. The Sheppard Family Cemetery and West Family Cemetery (both no longer used) are located in Robert Allerton Park.
Grain elevators Amenia—Allerton Station elevator (Section 17; T. 18 N., R. 5 E.) was built along the Decatur–Monticello–Champaign—Illinois Central railroad on the Allerton farm Piatt North No. 1 in 1912. The wooden elevator burned 15 April 2015. Two concrete silos remain on the site.
Schools Rural schools in T.18 N., R.5 E. included Excelsior School No. 66 (Section 7), Shady Nook School No.4, later No. 67 (Section 20), Stringtown School No. 65 (Section 8), Wildcat School No. 2, later No. 68 (Section 15), Willow Branch School No. 70 (Section 32). The rural schools were all demolished or converted to residences.
Major highways •
Interstate 72 •
Illinois State Route 48 Airports and landing strips • Norfleet Farms Airport ==Demographics==