The number of opposite-sex American couples living together has increased nearly 10-fold since the 1960s, demographers report.

• While there were only 439,000 such couples as of 1960, by 1998 the figure stood at 4.2 million.

• Studies show that those who cohabit before marriage are at a higher risk for divorce, up to 48 percent higher -- but experts say that trend may be abating.

• About one-half of previously married cohabitors and 35 percent of never-married cohabitors have children in the household, according to University of Michigan sociologist Pamela Smock.

• Most couples either breakup or marry within a year and a half.

Cohabiting couples are not confined to the young. Seniors may cohabit rather than marry to protect finances -- such as a pension from a previous spouse.

Sources: Karen S. Peterson, "Changing the Shape of the American Family," and "The Legal Path to Unmarital Bliss," USA Today, April 18, 2000.

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