The 16 inch gun M1919 (406 mm) was a large coastal artillery piece installed to defend the United States' major seaports between 1920 and 1946.

[6] It was mounted on a disappearing carriage in Fort Grant on the Pacific side of the Panama Canal Zone in 1914, where it served until scrapped in 1943.

The first of these was deployed to Fort Michie, Great Gull Island, New York on a unique all-around-fire M1917 disappearing carriage, with elevation increased from 15° to 30°.

[11] Based on the Coast Artillery's experience operating heavy weapons in World War I, especially the French-made 400 mm (15.75 inch) Modèle 1916 railway howitzer, the M1919 barbette carriage was designed with an elevation of 65° to allow plunging fire as enemy ships approached.

[16] By late 1943, the threat of a naval attack on the United States had diminished, and with two or four 16-inch guns in most harbor defenses, construction and arming of further batteries was suspended.