?A post office was first established in the Decatur County community of Grand River in November 1881 with Harry Milligan serving as the first postmaster. In the post office’s 130-year history in the southern Iowa town, it was located in at least five different community buildings before moving to its current location. Its current storefront was previously shared with the Bob Snyder Barber Shop; the southern portion of the building is now unoccupied.

The Post Office shares the block with the local American Legion and Lions Club buildings.