[2] The township was named after the town and county of Monaghan in Ireland.

[4] The Gilbert Bridge was added to the National Register of Historic Places in 1989.

[5] According to the United States Census Bureau, the township has a total area of 12.9 square miles (33 km2), all land.

There were 881 housing units at an average density of 68.0 per square mile (26.3/km2).

16.6% of all households were made up of individuals, and 4.6% had someone living alone who was 65 years of age or older.