Tombigbee River
The state of Illinois is bordered by the Mississippi River and the Ohio River. The state of Kentucky is also bordered by both rivers.
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If you crossed the Mississippi River from Kentucky, you would be in the state of Missouri.
Arkansas borders the Mississipi in that manner.
illinois and arkansas
Springfield, Illinois and Frankfort, Kentucky border both the Mississippi and Ohio rivers.
Mississippi
Actually, it's the other way around. The name "Mississippi" means "Large river" in the language of the Chippewa Indians. The Mississippi river was already documented with that name as far back as 1695, on a map drawn by Robert Cavelier Sieur de La Salle, and many years later, the state was named after the river that borders it.
Five states are on the west side of the Mississippi River. The west side of the Mississippi River borders Iowa, Missouri and Arkansas. The river flows through Minnesota and Louisiana.
That would have to be Alabama. What state (Alabama) is next to a very large river (Mississippi River) that shares a name with one of the boarder state (Mississippi).
The anagram is Mississippi, a US state and the long river that borders it.