Petersburg Township was organized in 1866, and named for Peter Baker, an early settler.

13.6% of all households were made up of individuals, and 6.8% had someone living alone who was 65 years of age or older.

About 3.6% of families and 6.4% of the population were below the poverty line, including 2.9% of those under the age of eighteen and none of those 65 or over.

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

At the state level, Petersburg Township is located in Senate District 22, represented by Republican Doug Magnus, and in House District 22B, represented by Republican Rod Hamilton.