ECONOMIC

y social pressures, however, which make women feel less feminine and menfeel less masculine if they enroll in courses traditionally selected by the othersex.The study also relates lifetime work history to earnings for women whonever married. A year's experience has a much greater effect on singlewomen's earnings than on those of married women. Single women workmuch more continuously than married women, though less so than marriedmen. Some single women may choose not to make investments relatedto work because they expect to marry. But many look forward to careersand may therefore delay marriage or never marry at all. This career orientationis consistent with the relatively greater number of years of schoolingcompleted by single women compared to those who marry. It is also consistentwith their observed higher earnings. Estimates of hourly wage andsalary earnings from 1970 census data show that women 45 to 54 years ofage who had never married earned 20 percent more than married women,and 28 percent less than married men, but only 2 percent less than men whohad never married.There is then also a differential between the earnings of married and singlemen, and it may be taken as another illustration of how specialization withinfamilies may affect career patterns and earnings. Single men have somewhatlower labor force participation rates; they also work fewer hours per yearthan married men. In part this may result from a higher incidence of disability,which influences both marriage and work. Although they have greaterwork participation than married women, single women also have higherdisability rates than married women.Because of differences in life-cycle participation in the labor force bywomen and men, the experience of women does not bear the same relationshipto age as it does for men. Many women who have entered or reenteredthe market at older ages are really beginners. Men's earnings are at theirpeak when the men reach an older age, but women's earnings will representa mixture in which a small minority have high earnings because of theirconsiderable experience, but the majority have earnings closer to those at thestart of a career. As age increases, it is therefore not surprising that the earningsdifferential between women and men widens. For example, a comparisonof usual weekly earnings of workers who worked 35 hours a week or morein 1973 shows that the ratio of women's earnings to men's earnings declinedfrom 0.70 at ages 20-24 to 0.59 at ages 45-54 for high school graduates. Ofcourse the earnings ratios at older ages reflect the work histories of differentcohorts of women. If the younger women maintain a greater attachment tothe labor force during their lifetime (and there is some evidence that thisis the case), then the ratio of women's earnings to men's may not decline asmuch with age in the future.Differences in lifetime work experience also seem to explain why the ratioof black women's earnings to those of white women exceeds the ratio ofearnings of black men to those of white men (Table 40). Indeed, in the156