Niagara 6020 rests tender-to-pilot with a classmate in the terminal at Harmon, New York, in a view provided by William D. Volkmer. Photographer and date are not specified. The S-1b class had 25½x32-inch cylinders and developed a tractive effort of 61,570 pounds. Their trailing truck, which was not equipped with a booster engine, supported a firebox with 101 square feet of grate area. This, combined with an evaporative heating surface of 4,819 square feet and 1975 square feet of superheating surface, produced a maximum drawbar horsepower of 5070 at 62.5 miles per hour, the equivalent at the time of four diesel units. To remain within the Central's more restrictive clearances and still accommodate a boiler diameter great enough for this level of output, the Niagaras had no steam dome but used a dry pipe running the length of the boiler. Total weight of locomotive and tender was 891,000 pounds. By around 1950 these 4-8-4s were removed from service on the New York Central's eastern lines. No. 6020 was one of the last handful of Niagaras in service, being retired in 1956 after only ten years of operation.