US 302 reaches its eastern terminus at Forest Avenue's interchange with Interstate 295 (I-295) and U.S. Route 1 (US 1) at the southern end of the Back Cove neighborhood.

[1] Forest Avenue picks up the U.S. Route 302 designation from Bridgton Road at its crossing of the Presumpscot River on the border between Westbrook and the Riverton area of Portland.

In the Oakdale neighborhood, Forest Avenue develops central turning lanes between the Preble Street and Baxter Boulevard intersections.

Near University of Southern Maine's Glickman Library, Forest Avenue passes through the cloverleaf intersection formed by I-295's exits 6A and 6B.

In 2012, the City of Portland completed a five-year Transforming Forest Avenue study, which envisioned a move away from the strip-mall design evident in the one-mile stretch between I-295 and Woodfords Corner, instead favoring a pedestrian-friendly layout.