Boston and Maine 3713

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Boston and Maine No. 3713, nicknamed The Constitution, is the only survivor of the B&M’s P-4a class heavy 4-6-2 Pacifics. Built in December 1934 by Lima Locomotive Works for the Boston and Maine Railroad, it hauled passenger trains around New England and was designed with 80-inch driving wheels and a large boiler for high-speed service.

Key facts in brief:
- Type: steam 4-6-2 “Heavy Pacific”
- Builder: Lima Locomotive Works
- Built: December 1934
- Wheel arrangement: 4-6-2 (Whyte), 2′C1′ n2 (UIC)
- Driver diameter: 80 in
- Boiler pressure: 260 psi
- Cylinders: 23 in × 28 in
- Tractive effort: 40,918 lbf (52,800 lbf with booster)
- Weight: engine about 339,200 lb; tender 240,800 lb; total 580,000 lb
- Fuel/water: coal, 37,000 lb capacity; 12,000 gallons of water
- Service: delivered 1934, last run 1956; retired July 1956
- Official name: The Constitution (named December 11, 1937, after a student contest)
- Notable duties: hauled high-priority passenger trains in the New England region

After diesel power took over in the mid-1950s, 3713 spent time as a stationary boiler in Boston and even ran a Steam Safari excursion in 1956. In 1958, New England entrepreneur F. Nelson Blount purchased the locomotive for his Steamtown collection. It spent time on display at Edaville and in Wakefield before moving to Steamtown in Scranton, Pennsylvania, in the 1980s.

restoration and status:
- Restoration began in 1995 as Project 3713, a partnership between the National Park Service and the Lackawanna & Wyoming Valley Railway Historical Society, with the goal of returning 3713 to operating condition.
- The rebuild has included major work on the boiler, air compressors, feedwater heater, and the pilot assembly. Wheels were refurbished, a new firebox was built, and several safety components were replaced.
- As of 2025, restoration work on No. 3713 is ongoing at Steamtown National Historic Site. When finished, it is planned to be able to pull excursion trains and become a working flagship for the collection.
- Current owner: Steamtown National Historic Site (under ongoing restoration)
- The locomotive’s broader role in the P-4a group included five other locomotives (Nos. 3710–3714) built by Lima; 3713 remains the sole survivor of that heavy Pacific group.

Future plans originally envisioned that, once restored, 3713 would operate excursions and serve as a replacement for some other locomotives in the region.