Owosso Township, Michigan  Owosso Township, formally named Owosso Charter Township, is a charter township of Shiawassee County in the U.S. state of Michigan. The population was 4,821 at the 2010 census. The township borders the city of Owosso on the east, but the two are administered autonomously. In 1835, the township received its first settlers, Elias Comstock, Kilburn Bedell and Lewis Findley, Bedell's father-in-law. The first building at Big Rapids was built in 1836. The township's name sake is the American Indian Chief Wasso. Wasso and his tribe was moved from this area by the US under the 1836 treaty to a reservation. A post office was established at Big Rapids in November 4, 1838 with the name Owasso with postmaster Daniel Ball. In 1838, Big Rapids/Owasso was platted by Daniel Gould for the owners, Williams. Shiawassee County was organized as a single township with the same name on March 23, 1836. Owosso Township was split off from Shiawassee Township taking the northern half of the county which was eight township survey areas on March 11, 1837. On March 21, 1839, Middlebury and Fairfield township areas were split off from Owosso as Middlebury Township, while the survey area 7 north range 4 east was detached from the township and added to Vernon Township. On the following day, Caledonia was detached short 5 section from the full township survey area. On February 16, 1842, the missing section were transferred to Caledonia to make it a whole survey area. By 1844, the spelling Owosso for the community came into use. The organizational act of March 20, 1848 formed New Haven Township, consisting of New Haven and Hazelton survey areas, from the township's territory. On March 28, 1950, Rush township was created out the township's northern township survey area leaving the township with a single survey area. In 1859, Owosso was incorporated as a city. Before January 22, 1864, the Detroit and Milwaukee Railroad came through the township's west side and a station, Mungerville, opened there. On that date, a post office opened there with the same name under postmaster Philander Munger. The Mungerville post office changed its name on May 4, 1878 to Burton. The Owasso post office officially changed to the newer spelling on June 8, 1875.