Who would have thought it? You learn something new every day.
Some parts of the contiguous United States are not attached by land to the main body of US land.
Three are accessible by road only by travelling on Canadian soil:
Point Roberts, Washington
Elm Point, Minnesota
The Northwest Angle, Minnesota
One is not directly connected by land, but is accessible by road via bridges from New York and Vermont:
Alburgh is one of only four non-island locations in the 48 contiguous states not directly connected to them by land, the others being Point Roberts, Washington; Elm Point, Minnesota; and the Northwest Angle in Minnesota. However, there are bridges to Rouses Point, New York (U.S. Route 2) and Swanton, Vermont, as well as to North Hero island to the southeast. This makes it so that Alburgh is not a practical exclave, unlike the other locations not connected to the United States by land. Isle La Motte lies to the southwest.