To understand changes in U.S. demographics … check right at home first.

Just because the housing bubble of the mid-2000s resulted in foreclosures, a down economy, and more young people moving back in with Mom and Dad … don’t believe that more fundamental demographic changes aren’t continuing to have a long-term effect as well.

This is underscored by newly published data on American households issued by the U.S. Bureau of Census, which breaks down statistics on the more than 121 million households in the United States.

As of 2012, the average size of the U.S. household stood at 2.55 people. That’s a decline of about one person per household since 1950.

What’s contributed the most to the decline of this average has been the increase in single-person households. According to the Census Bureau, those households now account for more than a quarter of all households in the country:

One-person households: ~27% of total U.S. households
Two-person HHs: ~34%
Three-person HHs: ~16%
Four-person HHs: ~13%
Five-person HHs: ~6%
Six-person HHs: ~2%
Seven or more persons per household: ~1%

In fact, the number of single-person households has gone up five-fold since 1960. A major part of the reason is the large percentage of older Americans (age 75+) who live alone – more than half.

That compares to only a quarter of households headed by people under the age of 30.

Other interesting factoids from the Census Bureau stats reflect some of the changing social mores in American society:

There are nearly 8 million unmarried couples living together – more than double the figure less than a decade ago. (It was ~2.9 million in 1996).
Married households now make up fewer than half of all households. (In 1970, that percentage was over 70%.)

But one demographic statistic does seem to reflect the consequences of the recent economic recession and the contraction in the American labor force: As of 2012, only ~52% of married couples have both spouses in the labor force, which is down from ~56% reported in 2000.

These new stats come from the U.S. Census Bureau’s latest Annual Social & Economic Supplement to the Current Population Survey, the data for which was collected in March and April 2012 from a nationwide sample of approximately 100,000 addresses.