[2] In September, 1834, the Commissioners of Allen County created Root Township, which embraced all of present-day Marion Township, as well as a portion of present-day Adams County.

Adams County was created on February 7, 1835, leaving only a portion of Root Township still in Allen County.

[3] According to the United States Census Bureau, Marion Township covers an area of 34.88 square miles (90.35 km2); of this, 34.65 square miles (89.75 km2) is land and 0.23 square miles (0.59 km2), or 0.66 percent, is water.

[2] (This list is based in part on USGS data and may include former settlements.)

The township contains the following cemeteries: Antioch Lutheran, Bethel Baptist (defunct), Coleman family (defunct), Emmanuel Lutheran, Hall (disappeared), Morton family (defunct), Poe/Williamsport, St. John's Lutheran (defunct), St. Joseph Hessen Cassel Roman Catholic, St. Paul's Lutheran (defunct), and Thompson family (defunct).