PHILADELPHIA - Despite what it may feel like, the average work week has not increased for most Americans in the past 30 years.

American feel more squeezed for time, however, because they are less likely to have someone at home devoted exclusively to family concerns, thus creating heightened time pressures and increased conflict between work and private life, according to a study by a University of Pennsylvania sociologist published today in the Review of Social Economy.

"The rise of the dual-earner and single-parent families, both of which rely on employed women, has reduced the amount of unpaid familial support at home and increased the pressure on many American workers," said Jerry A. Jacobs, Ph.D., professor of sociology at Penn. Since 1970, the proportion of couples with only a male breadwinner in the labor market has declined from a bare majority in 1970 to slightly more than a quarter in 1997. At the same time, the proportion of dual-earner couples rose sharply, from about a third of married couples in 1970 to about 60 percent in 1997.

The study, "Who are the overworked Americans?," documents the growing divide between those who work very long hours and those who are unable to find full-time employment. Using data from the Current Population Survey to analyze trends in working time in the United States over the past 30 years, Dr. Jacobs and the study's co-author, Kathleen Gerson, Ph.D., professor of sociology at New York University, argue that the American time squeeze is more varied than reported in books like The Overworked American (1991) and The Time Bind (1997), with a mismatch existing between working time and the preferences of American workers.

Long work weeks were founded to be prevalent among managers and professionals, with one in three men and one in six women in professional or managerial jobs working 50 or more hours a week. When surveyed, they said they wanted to work about five fewer hours a week.

But long work weeks were not found to be a universal phenomena. Many people working less than forty hours a week wanted to work more but were only able to find part time work.

NOTE TO REPORTERS AND EDITORS: A copy of the study is available by calling (215) 898-6460.