As of the 2010 census, its population was 1,501 and it contained 767 housing units.

[4] Marion Township was created from land given by Bainbridge, Hall, Columbia, Harbison, and Patoka townships.

[5] According to the 2010 census, the township has a total area of 32.66 square miles (84.6 km2), of which 31.71 square miles (82.1 km2) (or 97.09%) is land and 0.95 square miles (2.5 km2) (or 2.91%) is water.

[4] Marion Township is in Northeast Dubois County School Corporation.

In 1948 Harbison and Marion townships were planning a joint high school.