Below are the eight locations along the Mississippi River that were affected by an avulsion. They are presented from north to south:
Kaskaskia Island: The most well-known avulsion was at Kaskaskia Island, where a sizable chunk of Illinois now sits on the Missouri side. Kaskaskia isn't the only such oddity, though. It's possible to walk across the Missouri-Illinois state line in several places without crossing a bridge, riding a boat, or getting your feet wet.
|Note the green Illinois area on the west side of the Mississippi River is Illinois Territory.|
|Missouri is on the left, Illinois on the right.|
|This is the signage along US 61 at the entrance to Kaskaskia Island in St. Mary.|
|Illinois in the foreground, Missouri is in the background. The actual boundary is unmarked.|
|It's hard to tell from my maps, but this post apparently marks the state line in the middle of a field.|
|The boundary at Crains Island is quite complicated, shown as "Indefinite" on topographic maps.|
|The view from the boat ramp at Seventy-Six, looking from Missouri... into Missouri.|
|Looking north along Levee Road from Missouri into Illinois. It appears that the end of the pavement marks the state line.|
|The old river channel is now a U-shaped lake called Tower Island Chute. It still looks like a river but is cut off from the modern river channel by a levee.|
Missouri Sister Island: The name is an oxymoron: it's not an island, and it's not in Missouri. Sitting inside a sweeping 'S' bend of the river northwest of Cairo, this piece of Illinois has found itself on the Missouri side. Thanks to the crazy geography, the river actually flows to the northwest here -- and Missouri is east of Illinois. Yes, it's all rather confusing.
Compiled by Neil Gale, Ph.D.
 Avulsion is the rapid abandonment of a river channel and the formation of a new river channel. Avulsions occur as a result of channel slopes that are much less steep than the slope that the river could travel if it took a new course.