Roughly 22,000,000 of this M1 helmet were produced during the Second World War.
Two main companies produced the majority of the 2WW M1 helmets:
McCord Radiator & Manufacturing Co., located in Detroit, Michigan. McCord began production in June 1941 and produced twenty million M1 helmets.
(2) Schlueter Manufacturing Co., located in St. Louis, Missouri. Schlueter began producing two million helmets in January 1943.
In early 1941 Hawley Products Co. of St. Charles, Illinois developed a suitable liner for this steel helmet. Hawley produced a total of 3,977,000 helmet liners from July 9, 1941 until production ceased in November 1942.
Note: This style of helmet was used by the Canadian Forces from the 1970s to 1990s
As the war progressed, so did the washers that retained the liner’s suspension. The earliest helmet liners exhibited non-painted rectangular washers. In mid-1942 manufacturers switched to A-shaped washers.