Around 5.77 miles (9.29 km) long, it stretches from County Road, Portland's southwestern border with Westbrook, through a number of neighborhoods, before ending overlooking the Eastern Promenade on Munjoy Hill.

When what is now Portland was founded by British colonists in the early 18th century, the population settled primarily on the waterfront near today's India Street.

From the early settlement of Portland until the American Revolutionary War period, Back Street was considered the far edge of the town.

[7] The Second Parish Payson Memorial Church formerly stood to the right of City Hall, at Pearl Street,[8] where the Top of the Hill parking lot is today.

[9] Greater Portland Metro's route 1 (Congress Street), 5 (The Maine Mall), 7 (Falmouth Flyer), 8 (Peninsula Loop), 9A (North Deering via Stevens Avenue), 9B (North Deering via Washington Avenue) and the BREEZ, and Biddeford Saco Old Orchard Beach Transit's route 60 serve Congress Street.