In September 1940 the U.S. Congress passed the Burke-Wadsworth Act, the first peacetime draft of men aged 21-36 years in the history of the United States.
In November 1942 the draft ages were extended to ages 18-37 years for the war effort.
Until 1943, due to racist concerns about a mixed-race military, blacks were not drafted. In 1943 a “quota” was imposed, meant to limit the numbers of blacks drafted to reflect their numbers in the overall population (~ 10.6 %). Initially, blacks were restricted to “labor units,” but as the war progressed, they were finally used in combat.
By war’s end, approximately 34 million men had registered and 10 million had been inducted into the military.