The Atlantic Coast Line R-1 was a class of 12 4-8-4 Northern type steam locomotives built by Baldwin Locomotive Works (BLW) in 1938 and operated by the Atlantic Coast Line Railroad until the early 1950s.

In 1938, ACL ordered twelve R-1 4-8-4 Northerns from Baldwin Locomotive Works (BLW) to handle the heavier passenger trains, eliminating the need for double-heading and ran extra sections of many of the Richmond, Virginia to Jacksonville, Florida passenger trains.

Even after the rebuild with new disk driving wheels, they still had unacceptable amounts of dynamic augment at high speeds, as their counterbalancing weights were too high, which led to the locomotive's drivers pounding at high speeds and was said that the main drivers actually left the rails and repeatedly slammed back down, kinking rails and damaging track alignment for miles.

1800, 1801, 1806, 1807, 1808 and 1809 ran even more smoothly once they were fitted with lightweight pistons by Timken, piston rods, cross heads, and, probably most important, tapered main rods with roller bearing wrist pins.

The weight of the tender, fully loaded was 217 short tons (194 long tons)[3] In 1953, ten of the R-1 tenders were sold to the Norfolk and Western Railway (N&W), where they were paired with their Y4 class 2-8-8-2 compound mallets, until they were all scrapped in 1958.