The first post office in Wapello County was established in the community of Sac and Fox Agency on December 23, 1843. By 1849, the name of the office was changed to Agency City, with the word “City” officially dropped from the name in 1883. Since 1938, the Post Office has been located in a two-story brick building which houses the City Hall, Public Library and Olive Branch Masonic Lodge #21.