Foster Township is located in Madison County, Illinois, in the United States.

As of the 2010 census, its population was 4,091 and it contained 1,663 housing units.

[2] Foster is the name of Oliver Foster, a pioneer settler and native of New Hampshire.

[3] According to the 2010 census, the township has a total area of 31.34 square miles (81.2 km2), of which 30.86 square miles (79.9 km2) (or 98.47%) is land and 0.48 square miles (1.2 km2) (or 1.53%) is water.

This Madison County, Illinois location article is a stub.