Mackinaw River

Mackinaw River
Mackinaw River near Tremont, Illinois
Basin features
Main source	Ford County east of Sibley, Illinois 40°35′20″N 88°21′59″W / 40.5889233°N 88.3664421°W / 40.5889233; -88.3664421 (Mackinaw River origin)
River mouth	Confluence with the Illinois River near Mapleton, Illinois 443 ft (135 m) 40°33′06″N 89°43′56″W / 40.5517055°N 89.7323284°W / 40.5517055; -89.7323284 (Mackinaw River mouth)Coordinates: 40°33′06″N 89°43′56″W / 40.5517055°N 89.7323284°W / 40.5517055; -89.7323284 (Mackinaw River mouth)
Progression	Mackinaw River → Illinois → Mississippi → Gulf of Mexico
Physical characteristics
Length	130 mi (210 km)
GNIS ID	403283

The Mackinaw River is a 130-mile-long (210 km)tributary of the Illinois River in the U.S. state of Illinois. Its watershed covers approximately 1,136 square miles (3,000 km²), and contains some of the most productive agricultural land in the United States. The river itself maintains some of the highest quality streams in the state and provides habitat for 60-70 native fish species and 25-30 species of mussels. Its name, also spelled Mackinac, is derived from the Ojibwe word mikinaak meaning "turtle".

The Mackinaw River begins near Sibley, Illinois, in Ford County. From its headwaters the river flows west through McLean County, where it provides drainage to part of the Bloomington–Normal metropolitan area, and Woodford County. It continues west and then southwestward through Tazewell County before flowing into the Illinois River just south of Pekin.

The river flows through three natural divisions, including the Grand Prairie, Upper Mississippi River and Illinois Bottomlands, and Illinois and Mississippi Sand Areas. Early in its life, several thousand years ago following the Wisconsin glaciation, it cut through several moraines, which influenced the structure of the riverbed. The upper section of the watershed is marked by a series of pools and fast-flowing riffles. The character of the river downstream of the moraines is markedly different, with a relatively wide floodplain, large meanders and erosion-prone sandy banks. Its principal tributaries are Panther, Walnut and Money creeks, and the Little Mackinaw River.