Interstate 81 is an interstate highway in the eastern part of the United States. Its southern terminus is at Interstate 40 near Dandridge, Tennessee; its northern terminus is at Fishers Landing, New York at the Canadian border where the Thousand Islands Bridge connects it to Ontario provincial highway 401, the main freeway leading from Windsor-Detroit and Toronto to Montréal.

Distances by state

Major cities along the route

• Bristol, Virginia
• Roanoke, Virginia
• Harrisonburg, Virginia
• Winchester, Virginia
• Hagerstown, Maryland
• Harrisburg, Pennsylvania
• Wilkes-Barre, Pennsylvania
• Scranton, Pennsylvania
• Binghamton, New York
• Syracuse, New York

Intersections with other Interstates

• Interstate 40 near Dandridge, Tennessee, northeast of Knoxville
• Interstate 26 and Interstate 181 between the Tri-Cities, Tennessee
• Interstate 77 in Wytheville, Virginia. They stay joined for about 10 miles (16 km), and go in opposite directions.
• Interstate 64 in Lexington, Virginia. They stay joined until Staunton, Virginia.
• Interstate 66 in Middletown, Virginia
• Interstate 70 in Hagerstown, Maryland
• Interstate 76 in Carlisle, Pennsylvania
• Interstate 83 in Harrisburg, Pennsylvania
• Interstate 78 in Bordnersville, Pennsylvania
• Interstate 80 in Saint Johns, Pennsylvania
• Interstate 84 in Scranton, Pennsylvania
• Interstate 88 in Binghamton, New York
• Interstate 90 in Syracuse, New York

Spur routes

• I-181 - Spur to Kingsport, Tennessee. Once also connected to Johnson City, Tennessee, which is now Interstate 26, since September 2003.
• I-381 - Bristol, Virginia
• I-581 - Roanoke, Virginia
• I-481 - Syracuse, New York

Notes

This road was originally a "line on a map" Interstate. For many years, it existed so more people can have a path through the Appalachians than to relieve congestion on that busy Roanoke-Harrisburg route.

However, I-81 has become a major route for interstate truck transportation in recent years. Trucking companies that have tired of fighting big-city congestion along Interstate 95 are now opting to use this less congested inland route. Virginia has decided to widen its entire portion of I-81 to a minimum of four lanes in each direction to accommodate increased truck traffic. The new Virginia I-81 would completely separate car and truck traffic. For more comprehensive information on Virginia's plans for the I-81 corridor, see this site.

I-81 runs together with Interstate 77 in Wytheville, Virginia for about 10 miles (16 km), but the two go in opposite directions, creating a wrong-way multiplex. Motorists traveling northbound on I-81 are also traveling southbound on I-77, though they are actually going east. Likewise, motorists traveling southbound on I-81 are also traveling northbound on I-77, though they are actually going west.

I-481 around Syracuse, New York was originally called I-281.

There was an eastern branch, called I-81E, that was a spur from Scranton to Pocono in Pennsylvania. That highway is now I-380.

At I-81's northern terminus, a toll bridge over the St. Lawrence River connects it to unsigned Highway 137, a short link to the MacDonald-Cartier Freeway (ON Provincial Route 401) in Ontario. Not too far to the east lies the 'real' continuing freeway, Highway 416 leading into Ottawa.