I-81 weather conditions, radar and forecast information. Interstate 81 is an 854-mile-long highway that runs from Dandridge, Tennessee in the south up to the Canadian border at Wellesley Island, New York. I81 follows the Appalachian Mountains through Tennessee and Virginia.
It is the longest interstate in Virginia and since it is mostly rural it provides service to smaller cities and is heavily used by the trucking and cartage industry. Upon approaching the Canadian border at its end, I-81 crosses the St. Lawrence River using the Thousand Islands Bridge.