For those of you who haven't been keeping up on the latest household trends, the story lines is down. In fact, the latest report from the Bureau of the Census ought to be entitled "The Incredible Shrinking American Household."

The outline is fairly simple, even stark: In 1930, there were, no average, 4.1 persons living in each household. By 1950 there were 3.5. By 1970, there were 3.1.

Today, there are 2.8 persons per household, and it looks as if we haven't bottomed out yet. In Washington, trendy capital of America, there are only 2.39 people per household. In Manhattan, they are pushing for the singles prize with only 1.96.

But do not fret. We are not about to disappear mathematically. It's just that more and more of us are living with fewer and fewer of us. We have increased the number of households and decreased the number of people living in them. At this rate, by the turn of the century each American will be living in his or her own home.

These figures are fascinating to me because they say something about the role of choice in our lives.

For a long time, we have been decrying "the breakdown of the family," "the breakup of society," even loneliness, as if it were something happening to us, the poor innocent victims. Now we know that we aren't shrinking because we swallowed some strange toxic substance. We have willingly signed up for this household reduction plan.

The Census Bureau figures confirm what came out in a report on the family by Harvard-MIT's Joint Center for Urban Studies. Last spring, the authors, Mary Jo Bane and George Masnick, showed that in terms of family life, too, most of the changes came from the choices people were making.

One of the biggest changes in household size, for example, comes from the record number of people living alone. In 1790 only 3.7 percent of American households had one person in them; 160 years later, in 1950, 10.9 percent of households had one person. But in the next 30 years, that number more than doubled to 22 percent.

The statistical jumps came during the 1960s and 1970s. The "new people living alone are the young, the divorced and the old. During this period, men and women in their 20s left their parents' home to live alone. They no longer had to be married in order to have their own apartment.

The elderly, including widows, are now much less likely to move in with relatives. While it is impossible to describe widowhood as a "choice," the more economically secure a widow is, the more likely she is to live alone. Those who can afford independence seem to prefer it.

Divorce, another sort of choice (for at least one of the parties), is part of the saga of shrinkage. The divorced, like the widowed, also are less likely to move in with relatives and more likely to set up their own, smaller, households.

There are many other ways we have pursued this descending story line. Census Bureau people have pointed to the declining birth rate, the postponement of marriage and parenthood.

There is, for example, a great deal of nostalgia today for the "three-generation" family, but very little commitment to living in it. More of us talk wistfully about the warmth of a large family, but fewer of us are willing to risk the pressure of it. We express some longing for community, but we build separate lives.

I don't know whether we've lost the ability to share, or gained the luxury of private space. I don't know whether we are released from the strains of living with others, or locked into solitary confinement. I'm not even sure whether these choices make us freer or just more lonely.

But there is something spooky about the incredible shinking household. As the numbers head toward the single digit, maybe what we've swallowed is a line that finally diminishes each of us.