In 2008, more than 537,000 young adults between the ages of 18 and 24 were active enlisted members in the armed forces. These young adults represented 1.8 percent of the resident population (defined here as persons in the 50 U.S. states and the District of Columbia). Across all age groups, more male than female young adults were in the armed forces. For example, approximately 85,000 males between the ages of 18 and 19 were in the armed forces in 2008, compared with about 16,000 females in the same age group.
The number of young adults serving in the armed forces fluctuated between 2000 and 2008, reaching a high of about 579,000 enlisted members in 2003. However, there were differences in the trends by sex and age group. Between 2000 and 2008, the number of 18- to 19-year-olds serving in the armed forces decreased for both males and females. For males, the number decreased from about 109,000 in 2000 to 85,000 in 2008. Over the same time period, the number of 18- to 19-year-old females serving in the armed forces decreased from 24,000 to about 16,000. The number of 20- to 21-year-olds in the armed forces peaked in 2003 for males (174,000) and in 2002 for females (35,000) and then decreased for both sexes to 152,000 males and 26,000 females in the armed forces in 2008. In contrast, the number of 22- to 24-year-old males in the armed forces increased from 179,000 in 2000 to about 223,000 in 2008. However, the number of 22- to 24-year-old females who served in the armed forces increased from 34,000 in 2000 to 42,000 in 2004, and then decreased to 37,000 in 2008.