When NP neared completion in 1883, a fleet of locomotives was ordered for main line operation. Included was No. 342, a sleek Standard designed for fast passenger service. The engine was assigned to the Montana Division and it hauled hundreds of the first transcontinental trains. Renumbered 684 in 1898, the engine continued in mainline operation until coming of the ten-wheelers. Then she was assigned to the Yellowstone Park Branch between Livingston and Gardiner--quite a swanky deal at the time since the railway was the only access to the first national park. Sporting bright red wheels, polished brass and spotlessly clean, 684 hauled any number of notables to Yellowstone. Again replaced by heavier power, 684 worked out of Billings on the Bridger branch until 1928 when she was sold to the Nez Perce & Idaho Railroad, a 13-mile line between Nez Perce and Craigmont, Idaho.