Illinois River
The
Illinois River is a principal tributary of the
Mississippi River, approximately 273 miles (439 km) long, in the state of
Illinois in the
United States. The river drains a large section of central Illinois, with a drainage basin of 40,000 square miles (
104,000 km²). The river was important among
Native Americans and early
French traders as the principal water route connecting the
Great Lakes with the Mississippi. The colonial settlements along the river formed the heart of the area known as the
Illinois Country. After the construction of the
Illinois and Michigan Canal and the
Hennepin Canal in the
19th century, the river's role as link between
Lake Michigan and the Mississippi was extended into the era of modern industrial shipping.
It is formed by the confluence of the
Kankakee and
Des Plaines rivers in western
Grundy County, approximately 10 mi (16 km) southwest of
Joliet. It flows west across northern Illinois, passing
Morris and
Ottawa, where it is joined by the
Mazon River and
Fox River. At
La Salle it is joined by the
Vermilion River, then flows west past
Peru, and
Spring Valley. In southeastern
Bureau County it turns south at an area known as the "Great Bend", flowing southwest across western Illinois, past
Lacon and downtown
Peoria, the chief city on the river.
South of Peoria it is joined by the
Mackinaw River and then passes through the
Chautauqua National Wildlife Refuge. Opposite
Havana it is joined by the
Spoon River. Opposite
Browning it is joined by the
Sangamon River. It is joined by the
La Moine River approximately 5 mi (8 km) southwest of
Beardstown.
South of its confluence with the La Moine, it turns south, flowing roughly parallel with the Mississippi across southwestern Illinois. It is joined by the
Macoupin Creek on the border between
Greene and
Jersey counties, approximately 15 mi (24 km) upstream from its confluence with the Mississippi.
For the last 20 mi (32 km) of its course, it is separated from the Mississippi by only 5 mi (8 km). It joins the Mississippi near
Grafton, approximately 25 mi (40 km) northwest of downtown
St. Louis and approximately 20 mi (32 km) upstream from the confluence of the Missouri and the Mississippi.
South of
Hennepin, the Illinois River is actually following the ancient channel of the
Mississippi River. The
Illinoian Glaciation, about 200,000 to 125,000 years before present, blocked the Mississippi near
Rock Island, diverting it into its present channel. After the glacier melted, the Illinois River flowed into the ancient channel. The
Hennepin Canal roughly follows the ancient channel of the Mississippi upstream to Rock Island.
The modern channel of the Illinois River was shaped in matter of days by the Kankakee Torrent. During the melting of the
Wisconsin Glacier, about 10,000 years before present, a lake formed in Indiana, comparable to one of the modern
Great Lakes. The lake formed behind the terminal moraine of a substage of that glacier. Melting ice to the north eventually raised the level of the lake so that it overtopped the moraine. The dam burst, and the entire volume of the lake was released in a very short time, perhaps a few days.
Because of the manner of its formation, the Illinois River runs through a deep canyon with many rock formations. It has an "underutilised channel", a channel that is far larger than would be needed to contain any conceivable flow in modern times.
The Illinois River valley was one of the strongholds of the
Illiniwek confederation of Native Americans. The French first met the natives here in
1673. The first
European settlement in the state of Illinois was the
Jesuit mission founded in
1675 by Father
Jacques Marquette on the banks of the Illinois at
Starved Rock. In
1680,
Robert Cavelier de La Salle built the first fort in Illinois, Ft. St. Louis, at Starved Rock and later relocated to the present site of Creve Coeur, near Peoria, where the Jesuits relocated.
From
1905 to
1915, more freshwater fish were harvested from the Illinois than from any other river in the United States except for the
Columbia River. The river was once a major source of
mussels for the shell button industry.
Overfishing, habitat loss due to heavy siltation and pollution have eliminated most commercial fishing except for a small mussel harvest to provide shells to seed
pearl oysters overseas. It is still commercially fished downstream of the Rt. 89 bridge at Spring Valley. The river is still an important sports fishing resource with a world class Sauger fishery.
The river serves as a water source for many Central Illinois towns and cities, including
Jacksonville, Illinois.
The Illinois forms part of a modern waterway that connects the
Great Lakes at
Chicago, Illinois to the Mississippi River. The waterway was originally established by the building of the
Illinois and Michigan Canal which connected the Illinois River to the
Chicago River. When the Chicago River was later reversed, the pollution and sewage of the city of Chicago flowed down into the Illinois River. The Illinois and Michigan Canal has since been replaced by the
Illinois Waterway including the
Chicago Sanitary and Ship Canal. The river is controlled by five locks and dams to facilitate river traffic. The waterway is heavily trafficked by barges transporting bulk goods such as grain and oil.
*
Bath*
Beardstown*
Browning*
Chillicothe*
Creve Coeur*
East Peoria*
Florence*
Hardin*
Havana*
Hennepin*
Henry*
Kampsville*
Kingston Mines*
La Salle*
Lacon*
Liverpool*
Marseilles*
Meredosia*
Morris*
Naples*
Naplate*
Oglesby*
Ottawa*
Pekin*
Peoria*
Peoria Heights*
Peru*
Rome*
Seneca*
Spring Bay*
Spring Valley*
Valley City"Geology Underfoot in Illinois", Raymond Wiggers, 1997
*
List of Illinois rivers
