The Snake River forms part of Oregon's eastern border
The Connecticut River forms the eastern border of Vermont. The river is 410 miles long and is the longest river in New England.
Georgia's eastern border is the Atlantic Ocean
Mississippi River
The Mississippi River forms most of Arkansas's eastern border. Tennessee and Mississippi border Arkansas to the east across the Mississippi River.
While no river forms the eastern border of NY, the Hudson River is within 20 miles or so of the border.
the jordan river
The Jiamusi Ussuri River
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the Colorado river
The Mississippi River forms most of Arkansas's eastern border.
The Mississippi River forms the Western border of the States of Illinois, Tennessee, and Mississippi. The Mississippi River forms the Eastern border of the States of Iowa, Missouri, Arkansas, and Louisiana.