On an olive drab shield 2 1/2 inches (6.35 cm) in width and 3 3/4 inches (9.53 cm) in height overall (the parallel sides 2 1/2 inches (6.35 cm) in length with a 90 degree angle pointed base) a red Arabic numeral "1" (1 3/4 inches (4.45 cm) in height overall).
The numeral identifies the Division's designation.
The shoulder sleeve insignia was originally approved for the 1st Division on 31 October 1918, as a red number "1" and amended on 31 March 1927, to include the background of the insignia in the design. It was redesignated for the 1st Infantry Division on 19 August 1942. The insignia was amended to revise the description on 6 October 1972. (TIOH Drawing Number A-1-76)