Draft lottery (1969)

On December 1, 1969, the Selective Service System of the United States conducted two lotteries to determine the order of call to military service in the Vietnam War for men born from 1944 to 1950. These lotteries occurred during a period of conscription from just before World War II to 1973.

The lottery numbers assigned in December 1969 were used during calendar year 1970 both to call for induction and to call for physical examination, a preliminary call covering more men.

The days of the year (including February 29) were represented by the numbers 1 through 366 written on slips of paper. The slips were placed in separate plastic capsules that were mixed in a shoebox and then dumped into a deep glass jar. Capsules were drawn from the jar one at a time.

The first number drawn was 258 (September 14), so all registrants with that birthday were assigned lottery number 1. The second number drawn corresponded to April 24, and so forth. All men of draft age (born 1944 to 1950) who shared a birth date would be called to serve at once. The first 195 birthdates drawn were later called to serve in the order they were drawn; the last of these was September 24.

Also on December 2, 1971, a second lottery was held, with the 26 letters of the alphabet. Among men with the same birthdate, the order of induction was determined by the permutation ranks of the first letters of their last, first, and middle names. Anyone with initials "JJJ" would have been first within the shared birthdate, followed by "JGJ", "JDJ", and "JXJ"; anyone with initials "VVV" would have been last.

People soon noticed that the lottery numbers were not distributed uniformly over the year. In particular, November and December births, or dates 306 to 366, were assigned mainly to lower draft numbers representing earlier calls to serve (see figure). This led to complaints that the lottery was not random as the legislation required. Analysis of the procedure suggested that mixing 366 capsules in the shoe box did not mix them sufficiently before dumping them into the jar. ("The capsules were put in a box month by month, January through December, and subsequent mixing efforts were insufficient to overcome this sequencing.") Only five days in December—Dec. 2, 12, 15, 17 and 19—were higher than the last call number of 195; had the days been evenly distributed, 14 days in December would have been expected to remain uncalled. From January to December, the rank of the average draft pick numbers were 5 4 1 3 2 6 8 9 10 7 11 12. A Monte Carlo simulation found that the probability of a random order of months being this close to the 1–12 sequence expected for unsorted slips was 0.09%.

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