I-81

Interstate 81
Route information
Length:	854.89 mi (1,375.81 km)
Major junctions
South end:	I-40 in Dandridge, TN
	I‑77 near Wytheville, VA I‑64 from Lexington, VA to Staunton, VA I-70 at Hagerstown, MD I-76 / Penna Turnpike at Carlisle, PA I-78 at Union Township, PA I-80 near Hazleton, PA I-84 / I-380 near Scranton, PA I-90 / New York Thruway in Syracuse, NY
North end:	Highway 137 to Highway 401 on Thousand Islands Bridge at Wellesley Island, NY/Hill Island, ON
Location
States:	Tennessee, Virginia, West Virginia, Maryland, Pennsylvania, New York
Highway system
Interstate Highway System Main Auxiliary Suffixed Business Future

Interstate 81 (abbreviated I-81) is an Interstate Highway in the eastern part of the United States. Its southern terminus is at Interstate 40 in Dandridge, Tennessee; its northern terminus is on Wellesley Island (near Fishers Landing, New York) at the Canada–US border, where the Thousand Islands Bridge connects it to Highway 401, the main Ontario freeway connecting Detroit via Toronto to Montreal.

I-81 is the longest odd-numbered (and therefore the longest north-south) Interstate highway in which the number does not end with a 5, and the third longest Interstate highway in which the number does not end with a 0 or 5 after I-94 and I-64. Interstate 81 largely traces the paths created down the length of the Appalachian Mountains by migrating animals, American Indians, and early settlers. It also follows a major corridor for troop movements during the Civil War. These trails and roadways gradually evolved into U.S. Route 11. Interstate 81 parallels much of the older Route 11. Being mostly rural, it is heavily used as a trucking corridor, often as a bypass of the busier Interstate 95 to the east.

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Wikipedia