U.S. Federal Route 23 is a north-south expressway through Eastern Washtenaw County. This forms the eastern and northern portion of the loop around Ann Arbor. U.S. Rt. 23 passes thorugh the following towns in Washtenaw County. Milan Ann Arbor U.S. Rt. 23 is multi-plexed in Washtenaw County. BUSN Loop I-94, near Ann Arbor. Michigan State Route 14, at Ann Arbor.