Martinsburg Township was organized in 1878, and named for Martin Grummons, the son of a county official.

[3] According to the United States Census Bureau, the township has a total area of 36.5 square miles (94.4 km2), all land.

There were 85 housing units at an average density of 2.3 per square mile (0.89/km2).

20.8% of all households were made up of individuals, and 3.9% had someone living alone who was 65 years of age or older.

About 12.5% of families and 11.2% of the population were below the poverty line, including 13.8% of those under the age of eighteen and 8.0% of those 65 or over.