Boston & Maine Railroad #3666 4-6-2 Pacific class locomotive spent most of its life pulling intercity and commuter passenger trains out of Boston to points north, to such places as Concord, New Hampshire and Portland, Maine. On one particular night on September 10, 1939, the #3666 with train #2024, a Portland to Boston passenger run, was making its way over the Portsmouth Bridge which crosses the very turbulent Piscataqua River. This bridge had been previously damaged when a freighter hit it several years earlier. Even though there was a 3 mph speed limit on the bridge, the locomotive, tender and the first empty passenger coach fell into the River. The remaining coaches were disconnected from the falling coach causing a break with the air line causing the brakes to automatically be applied