http://en.wikipedia.org/wiki/Selective_Service_System
On March 29, 1975, President Ford signed Proclamation 4360, Terminating Registration Procedures Under Military Selective Service Act, eliminating the registration requirement for all 18–25 year old male citizens.[9]
On July 2, 1980, however, President Carter signed Proclamation 4771, Registration Under the Military Selective Service Act, retroactively re-establishing the Selective Service registration requirement for all 18–26 year old male citizens born on or after January 1, 1960.[10] Only men born between March 29, 1957, and Deceraber 31, 1959, were completely exempt from Selective Service registration.[11] The first registrations after Proclamation 4771 took place on Monday, July 21, 1980, for those men born in January, February and March 1960 at U.S. Post Offices. Tuesdays, Wednesdays and Thursdays were reserved for men born in the later quarters of the year, and registration for men born in 1961 began the following week