WASHINGTON (AP) _ Despite a widespread belief that the American family is disintegrating, family patterns in the 1990s are showing much more stability than they were 10 years ago, according to a private study.

One reason: The baby boom generation has reached middle age.

The American family of the 1960s was a married couple with two or more children in which the husband was the sole breadwinner, says the study by the Population Reference Bureau.

The family of the 1990s ``typically has only one or two children and both parents work outside the home,'' it says. ``Changing marriage and divorce patterns, the influx of married women into the labor force, the stagnation of men's wages, and the aging of the baby-boom generation all have played a role in the transformation of the family.''

``Middle age is the time of life when family responsibilities come to the fore,'' researcher Carol DeVita told a news conference.

One-third of families have children under 18, two-parent married couple families are on the increase and the average number of children women will have in their lifetime now is 2.0, the highest since 1972, she said.

``The major changes in the family structure are probably past,'' DeVita said.

California, of course, remains by far the most populous state with 31.6 million residents. Texas has assumed second place with 18.7 million, edging New York with 18.1 million. The rest of the top 10 in order last year were Florida, Pennsylvania, Illinois, Ohio, Michigan, New Jersey and Georgia.

Wyoming is the least populated.

The country's minority population is 26 percent. The District of Columbia leads the 50 states with a 75 percent nonwhite population. Hawaii is the only state where the majority of its residents are from minority groups, at 68 percent.

``New Mexico is on the verge of becoming majority minority,'' DeVita said. The state has a 50 percent minority population, followed by California with 47 percent, and Texas 46 percent.

Asian Americans had a median household income in 1994 of $40,500, the highest among racial and ethnic groups. Next was $35,000 for non-Hispanic whites. Blacks reported a median household income of $21,000, the lowest, just under the $23,400 for Hispanic households.

Nevada had the biggest population growth by percentage between 1990 and 1995, followed by Idaho, Arizona, Colorado, Utah, Washington, New Mexico, Georgia, Oregon and Texas. Connecticut, Rhode Island and the District of Columbia lost population.

In 1994, 683,000 legal immigrants and 121,000 refugees came to the United States. One of every three went to California.

Contrary to the popular image of aliens storming across the border at night, about half of undocumented aliens entered the country as legal immigrants _ often as tourists or students _ but stayed when their visas expired, DeVita said.

The number of illegal immigrants is estimated from 1.1 million to 2.9 million a year, but most leave voluntarily or are deported and only about 300,000 remain as permanent settlers, she said.