Since 1981, the preponderance of population growth has been in the South and West, 1986 population estimates show. California, Texas, and Florida accounted for 53 percent of the national population growth from 1980 to 1986, while Florida passed Illinois to become the fifth most populous state in 1986. Declines in energy-related industries, however, slowed growth in the South and West as growth rates fell sharply the last 3 years in Texas, Louisiana, and Utah. The nation's population continues to age, as the median increased from 30.0 years in 1980 to 31.7 years in 1986. Because of changes in the age structure, households have grown faster than the total population during the 1980s. There are more males than females in Alaska, Hawaii, Nevada, North Dakota, and Wyoming. Males under 18 are the majority in all states, but by age 18 to 24, women predominate in about half the states. The data are illustrated in charts and tables. (SM)