Portland Township is located in Whiteside County, Illinois. As of the 2010 census, its population was 422 and it contained 186 housing units.

Geography

According to the 2010 census, the township has a total area of 35.65 square miles (92.3 km), of which 34.73 square miles (90.0 km) (or 97.42%) is land and 0.92 square miles (2.4 km) (or 2.58%) is water.

Demographics

Historical population

Census	Pop.	Note	%±
2016 (est.)	409
U.S. Decennial Census