CONFLUENCE - Illinois River - Mississippi River - Grafton, IL
Posted by: 
NorStar
N 38° 58.100 W 090° 26.100
15S E 722222 N 4316391
The Illinois River, part of the network of navigable rivers of the Mississippi-Missouri system, is dwarfed by the Mississippi River as they merge at this location.
Waymark Code: WMWKHA
Location: Illinois, United States
Date Posted: 09/15/2017
Views: 1
In Grafton, at the Grafton Ferry ramp, is where the Illinois River merges with the mighty Mississippi River.
I designate this location as an easy access point to park and observe the merging of the two rivers. If you take the ferry, you cross the Illinois channel, then through an island, then the Mississippi channel to the far shore on the Missouri side. Using Google imagery, there are three islands that provide some separation between the two bodies. The point itself is to the west about a mile. There also is a bike path nearby where you can walk along the confluence. For about 20 miles upstream, the two rivers are separated by only 5 miles. The Pere Marquette State Park about four miles west has a visitor center with a very realistic 3-D map of the confluence to help orient you to to various features.
The Illinois River is a major riverway entirely within the state of Illinois. The watershed extends into Indiana and Wisconsin via tributaries that feed it. Today, it connects to Lake Michigan via canals through Chicago, and, thus, is an important waterway connecting the Great Lakes with the Gulf.
The Mississippi River is a massive river, even at this point above the confluence with the Missouri River, which is similar in size to the Mississippi. This river starts in Minnesota and drains parts of other states like Wisconsin, Iowa and the western edge of Illinois and the eastern part of Missouri.
The flows of both rivers are highly regulated and maintained by the Rock Island District of the U.S. Army Corps of Engineers. There are locks and dams on both rivers.
In early colonial times, the French explorer, LaSalle, rode down the Illinois to the Mississippi, then down the Mississippi to the Gulf.
Sources:
Wikipedia (Illinois River):
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visit link)
(La Salle Expeditions):
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visit link)
U.S. Army Corps of Engineers (Rock Island District):
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visit link)