It is a major interregional highway, connecting the Interstate 95 corridor to the Atlantic coast.

Major cities and towns along the length of SR 3 include Augusta, Belfast, Ellsworth, and Bar Harbor.

SR 3 continues east to the city of Belfast, where it interchanges with US 1 west of downtown.

Entering the Trenton township, the remainder of the route is designated as the Acadia All-American Road.

This was intentionally done to avoid confusion, as a motorist on the southern part of the island driving on SR 3 westbound is actually traveling east (and vice versa).

The bypass connected to North Belfast Avenue where SR 3 joined US 202/SR 9 and continued its existing route eastward.