Middlebury Township takes its name from John and William Palmer, who settled here in 1838 after moving from Middlebury, New York — itself named for their father's hometown of Middlebury, Vermont.
The township's first election was held in 1839 at the home of Moses Clark Jr., where William Palmer was chosen supervisor and John Slocum treasurer. Early settlers included Obed Hathaway and George Slocum; Slocum became the first postmaster when the village was renamed Middleburgh in 1848. Other early post offices — Hale (later Maple Valley) and Kenney's — served the area through the mid-1800s.
During World War II, Camp Owosso operated at the Owosso Raceway near Carland Road and M-21. The first 200 German prisoners of war arrived on May 30, 1944, and by July the camp held about 375. Under an Emergency Farm Labor program they worked on area farms and at regional canning factories for roughly eighty cents a day. After the war the camp was dismantled, its buildings sold to neighbors, and the racetrack returned to use.