THE CENSUS BUREAU reports there was no significant increase in the number of households in the United States in 1982. That's the first time the number of households has failed to rise in 20 years. Everyone agrees the recession was a factor: when times get tight, it's cheaper to double up. But this isn't the first recession in the last 20 years.

In the 1970s the nation's population increased 11 percent--a low figure historically--but the number of households increased by 30 percent--the highest rate in 100 years. Why? Elderly people chose to live in their own apartments rather than with their children; young people, women as well as men, moved out after school rather than stay home until marriage; married people got divorced in record numbers. Affluence helped let Americans make these choices: family income didn't go up much, but per- capita income did, which means that Americans used gains in income less to increase household income than to form new households. The decision to form a new household also reflected, in many cases, an attitude that one is better off liberated and alone than tied to others by obligations and responsibilities.

Is that attitude changing? No doubt it's true that some people felt unable to form new households in 1982 because their incomes fell in the recession. But the number of young people in the household- formation years remained high. The number of elderly people continued to increase more rapidly than did the population generally. The number of divorces reached its highest point in 1979, and has been falling since. The kind of people who chose to form new households in the 1970s continued to rise in 1982. But the number of households did not.

If the number of households increases sharply with economic recovery, then it may turn out that household formation was just postponed. But if attitudes have changed, all kinds of other changes may follow. The housing industry, which thrived through most of the 1970s by building new apartments and houses for newly formed households, will have less work to do. Ditto, perhaps, for the auto industry. Frozen gourmet dinners and restaurant meals may cease to be the fastest-growing segments of the food industry. A shift in focus from individual fulfillment to family responsibilities can change the way we live and work more than we can imagine. Watch the numbers.