I recently acquired this stampless cover and believe it was most likely sent in 1850.

The addressee, Sarah A. Town of Otsego, MI was the third wife of Oka Town, a prominent resident of Allegan County, Michigan.
The cover was without content and it bears no docketing indicating either the sender or the year mailed but I am assuming that it was sent to Sarah by Oka in 1850. I am making that assumption based upon the following:
- Sarah A. Eldred married Oka Town on October 17, 1847
- The postmark was used from 1849-53
- The 5c rate (1/2 ounce under 300 miles) was in effect from July 1, 1845 to June 30, 1851
- Oka Town was the Allegan County representative to the Michigan Constitutional Convention held in Lansing from June 3 to August 15, 1850.
Oka was the first probate judge of Allegan County (1835), he served several terms as Supervisor of Otsego township (1837, 1839-40, and 1848-49), and represented Allegan county in the State legislature in 1852-53.
Sarah was born January 2, 1826 and died on September 28, 1908. Oka was born in Stoddard, New Hampshire on July 2, 1806 and he died on March 24, 1895.