Purely on looks the Northern was one of the most aesthetically beautiful steam locomotive designs ever developed. While some of these handsome locomotives would receive streamlining even without such enhancements they were still a fine looking piece of machinery with a "streamlined" tender, long sweeping boiler, symmetrical wheel arrangement, and centered headlight. The 4-8-4 gained its name from the Northern Pacific where the locomotive was first operated in the 1920s. However, of all the popular steam designs ever put into service the 4-8-4 was the most widely renamed, from "Greenbriers" on the Chesapeake & Ohio to "Westerns" on the Denver & Rio Grande Western. In many ways the 4-8-4 was the pinnacle of steam power power and technology, which utilized only a single set of drivers. Before the diesel era caught on in the late 1930s, three-dozen of largest railroads in America put the locomotive into service in both passenger and freight operations. Surprisingly, despite their size, more than a half-dozen Northerns remain in operation today and several others are preserved.