Pennsylvania State Route 18 runs north-south in Western Mercer County. It goes from the Lawrence/Mercer County Line, near New Wilmington, to the Crawford/Mercer County Line, near Adamsville. PA St Rt 18 passes through the following towns in Mercer County. West Middlesex Hermitage Sharpsville Shenango Greenville Osgood PA St Rt 18 is multi-plexed in Mercer County. Pennsylvania State Route 358, at Greenville. Pennsyvlania State Route 58, at Greenville. PA St Rt 18 crosses the following highways in Mercer County. Interstate 376, near West Midlesex. Pennsylvania State Route 551, near West Middlesex. Pennsylvania State Route 318, at West Middlesex. Interstate 80, near West Middlesex. (NO Interchange) Pennsylvania State Route 760, near Wheatland. Pennsylvania State Route 518, near Hermitage. U.S. Rt. 62, at Hermitage. BUSN U.S. Rt. 62, at Hermitage. Pennsylvania State Route 518, near Hermitage. Pennsylvania State Route 258, at Sharpsville. Pennsylvania State Route 846, near Greenville. Pennsylvania State Route 358, near Greenville. Pennsylvania State Route 58, near Greenville. Pennsylvania State Route 358, near Greenville. Pennsylvania State Route 58, near Greenville.
