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 Canadian border, where the Thousand Islands Bridge connects it to Highway 401, the main Ontario freeway connecting Detroit via Toronto to Montreal.

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 Canadian border, where the Thousand Islands Bridge connects it to Highway 401, the main Ontario freeway connecting Detroit via Toronto to Montreal.