Modification
Lottery procedure was improved next year although public discontent continued to grow until "authority to induct expired on June 30, 1973.".
In 1970, covering 1951 birthdates for use during 1971 (sometimes called the 1971 draft), scientists at the National Bureau of Standards prepared 78 random permutations of the numbers 1 to 365 using random numbers selected from published tables. From the 78 permutations, 25 were selected at random and transcribed to calendars using 1 = January 1, 2 = January 2, ... 365 = December 31. Those calendars were sealed in envelopes. 25 more permutations were selected and sealed in 25 more envelopes without transcription to calendars. The two sets of 25 envelopes were furnished to the Selective Service System.
On June 2, an official picked two envelopes, thus one calendar and one raw permutation. The 365 birthdates (for 1951) were written down, placed in capsules, and put in a drum in the order dictated by the selected calendar. Similarly, the numbers from 1 to 365 were written down and placed into capsules in the order dictated by the raw permutation.
On July 1, the drawing date, one drum was rotated for an hour and the other for a half-hour (its rotating mechanism failed). Pairs of capsules were then drawn, one from each drum, one with a 1951 birthdate and one with a number 1 to 365. The first date and number drawn were September 16 and 139, so all men born September 16, 1951, were assigned draft number 139. The 11th draws were the date July 9 and the number 1, so men born July 9 were assigned draft number 1 and drafted first.
Read more about this topic: Draft Lottery (1969)