Mercer County

Mercer County forms part of Ohio’s western border.  Its largest feature is the Grand Lake St. Mary’s State Park and is the largest inland lake in Ohio.  The lake was originally constructed to feed the Miami and Erie Canal.  Mercer County has two rivers, the Wabash and St Mary’s.  The Wabash River is part of the Gulf of Mexico watershed, while the St Mary’s is part of the Lake Erie watershed.