[3] According to the United States Census Bureau, the township has a total area of 36.1 square miles (93 km2), all land.

The racial makeup of the township was 97.54% White, 2.05% Native American, 0.41% from other races.

About 7.2% of families and 8.4% of the population were below the poverty line, including 8.5% of those under the age of eighteen and 18.4% of those 65 or over.

Grange Township is located in Minnesota's 1st congressional district, represented by Mankato educator Tim Walz, a Democrat.

At the state level, Grange Township is located in Senate District 22, represented by Republican Doug Magnus, and in House District 22A, represented by Republican Joe Schomacker.