Actually, this woman was a draft service worker during WWII. Men 18-65 and were required to register and keep the card on them at all times. Men age 18-45 were subject to military service. From 1940 until 1947 – when the wartime selective service act expired – over 10,000,000 men were inducted.
This cartoon in the Saturday Evening Post depicted a draft board scraping the bottom of the barrel.