Originally built of stone masonry in 1830, Songo Lock was a vital link in the 50 mile waterway from Portland Harbor to Harrison at the head of Long Lake until the railroad arrived in 1869. At one time, 100 canal boats freighted lumber out and supplies in through the waterway. These boats were 65 feet long and were towed by horses and oxen through the canal, sailed across the lakes, and poled up the Songo River. Twenty-seven similar locks were constructed in the canal to compensate for the 260 foot difference in elevation between Sebago Lake and sea level. The canal had been considered in 1791; in 1821 the first Maine Legislature granted a charter to the Cumberland and Oxford Canal Corp. to dig a canal from Waterford to Fore River, with a survey made and cost estimated at $130,804. In 1823 the second Legislature granted land and authorized a $50,000 lottery, which netted $37,000. In 1825 the Canal Bank of Portland was chartered with a capital of $300,000 and a provision that 25 percent of its stock be invested in the Canal Company. Work started in 1828 and was completed in 1830 at a total cost of $206,000, with the Canal Bank taking a mortgage for the balance. The Canal Co. was sold for $40,000 in 1857, the canal was abandoned after the last boat passed through in 1872, and traces of the old canal can still be seen between Sebago Lake and Portland while this lock remains in service for pleasure boats.