The Milwaukee Road Class "A" was a class of high-speed, streamlined 4-4-2 "Atlantic" type steam locomotives built by the American Locomotive Company (ALCO) from 1935 to 1937 to haul the Milwaukee Road's Hiawatha express passenger trains.

The only change during their service life was the addition of a Mars Light beneath the winged emblem on the nose in 1947.

The successor Milwaukee Road class F7 was even more powerful, with a claimed top speed of 125 mph (201 km/h).

The main rods connected to the first pair of driven wheels rather than the (more conventional) second; again, this reduced the reciprocating mass as well as providing more even power throughout the stroke.

The streamlined casings were designed to open easily for servicing; the front end had clamshell doors ahead of the smokebox.