All men aged 18 to 26 “have been automatically registered in the U.S. Army.”
It’s important to know that even though he is registered, a man will not automatically be inducted into the military. In a crisis requiring a draft, men would be called in a sequence determined by random lottery number and year of birth. Then, they would be examined for mental, physical, and moral fitness by the military before being deferred or exempted from military service or inducted into the Armed Forces. [...] Men serving in the military on full-time active duty do not have to register if serving continuously from age 18 to age 26. Those attending the service academies do not have to register. However, if a man joins the military after turning 18 or leaves the military before turning 26, he must register. [...] Members of the Reserve and National Guard not on full-time active duty must register.