It connects the Greater New Haven area to Northwestern Connecticut via the western suburbs of Waterbury.

About 0.6 miles later, it leaves Whalley Avenue for Amity Road at the southern end of Route 69.

It then passes under the Wilbur Cross Parkway (Route 15), offering southbound access only.

It then meets the Route 8 expressway at Exit 26 before crossing the Naugatuck River into the downtown area.

It then becomes a minor arterial road north of town, and passes by the eastern end of Route 132 before entering Morris.

Leaving Litchfield, Route 63 becomes a minor rural road as it passes into Goshen.