tributary of the Mississippi River rising in the Ozark Mountains, near Salem in Dent county, southeastern Missouri, U.S. The river winds 207 miles (333 km) generally north, northeast, and southeast through the limestone Meramec Caverns and Meramec State Park (near Sullivan) to enter the Mississippi River 20 miles (32 km) below St. Louis. Lead was mined along its banks in the 1700s, and the river was used by settlers and traders. A ferry, said to be the first in Missouri, was established near its mouth in 1776. Its main tributaries are the Bourbeuse and Big rivers. The Meramecian series of limestone rocks was named for the river. Meramec is possibly derived from an Algonquian word meaning “catfish.”