Hat worn by those in the 42nd Infantry Division, also known as the Rainbow Division. One side has a small rainbow with a blue 42 under it, other has "Rainbow Division" printed in blue.
John W. Swartzwelder, Jr. and Nancy Joyce (Koger) Swartzwelder
Woodrow Wilson Presidential Library & Museum
United States. Army. Infantry Division, 42nd, “Rainbow Division Hat,” No date, T100089, Thomas J. Koger Collection, Woodrow Wilson Presidential Library & Museum, Staunton, Virginia.