South Portland sits across the Fore River from Portland, on the south shore of Portland Harbor, with the working waterfront, oil terminals and shipyards along its northern edge. The Casco Bay Bridge connects Knightville with downtown Portland, and I-295 runs along the city's northwestern edge. The Maine Turnpike runs along the west side with an interchange at the Maine Mall. Broadway is the main east-west street, US 1 runs through Thornton Heights toward Scarborough, and Route 77 heads south along Ocean Street into Cape Elizabeth.
The Maine Mall area is the region's main shopping district, and traffic on Maine Mall Road, Gorham Road and Running Hill Road backs up on weekends and through the holiday season. Broadway carries steady traffic between the bridge and the mall, with stoplights the whole way. The older neighborhoods near the harbor, like Knightville, Ferry Village and Meetinghouse Hill, have narrow streets, modest homes and short driveways. Farther west, Thornton Heights and the neighborhoods around the mall have more space and more traffic. Ocean Street and Cottage Road carry traffic toward Cape Elizabeth's beaches and lighthouses, and summer weekends bring heavy visitor traffic.
Portland International Jetport sits on the city's northern edge, shared with Portland. South Portland Bus Service connects with Portland's METRO and runs along Broadway and to the mall. Most people drive, though, and many commute across the bridge into Portland every day. A repair at home or work saves time and a crossing over the bridge. The oil terminals and shipping facilities along the waterfront also bring steady truck traffic to Broadway and Main Street.