U.S. Rt. 45 is one of few highways running through Massac County. This is the southern most county in Illinois that U.S. Rt. 45 runs through. U.S. Rt. 45 passes through the following towns in Massac County. Mermet
U.S. Rt. 45 is not multi-plexed in Massac County U.S. Rt. 45 interstects the following highways in Massac County. Illinois State Route 169, near Mermet.