There has been a dramatic shift in this country in the past couple of decades toward more people being single, and if and when they marry, marrying at a much later age. But when journalist Rebecca Traister began studying this trend, she found there have been large numbers of single women at periods in the past, and they have often had a profound impact on social change.

Traister, the author of the new book, “All the Single Women: Unmarried Women and the Rise of an Independent Nation,” spoke to about 150 people at Lehigh University March 30, a talk sponsored by the Friends of the Lehigh University Libraries. Traister, who described herself as an alumna of the Lehigh University daycare center, is the daughter of a Lehigh English professor emeritus, Barbara Traister.

She has written for a number of magazines, often about women in politics, media and entertainment from a feminist perspective.

She began researching the book when she learned there are now more unmarried than married adults in the U.S. and wondered how this demographic change is affecting women.

“I thought going in it was a contemporary phenomenon,” she said, but as she researched, she “realized the history of women living outside marriage had already profoundly defined how the country was organized.”

In 19th century New England, single women were briefly allowed to own land, and those landowners were the first women to petition for voting rights (at the time, only land-owning white men had the vote).

But even their right to own land was soon taken away, as the men in power realized how much power that right gave to single women. Married women at that time were legally subjected to the practice known as couverture, in which their identification was covered by the identification of their husbands. Remnants of these laws are still with us, Traister said, noting it was not until 1974 that married women could obtain credit in their own names, and there were no laws against marital rape prior to that.

In the 19th century, American men started moving west, leaving women behind and creating a population of single middle class white women in the East. The thousands of military men killed in the Civil War only exacerbated the gender disparity, with the rate of spinsterhood peaking between 1865 and 1875.

As a result, in popular culture, the concept of “single blessedness” arose, suggesting that single women, instead of serving their family, as married women were expected to do, “served all of us.” At the same time, the need to educate children was recognized, and the profession of teaching became “a perfect match” for single women. This led to single women being hired as teachers in increasing numbers, at least in part because they could be paid less than men, since it was assumed that unlike men, they did not need to support a family. They were also, of course, expected to resign if they married.

Another “serving” profession, nursing, became more necessary with the outbreak of conflicts like the Civil War and the Crimean War, and attracted many single women.

The Industrial Revolution in the 19th century led to another path for women, who were hired in large numbers to work in factories and mills. The work was dangerous and low-paying, but still gave them some economic self-sufficiency.

Meanwhile, marriage in the 19th century could be grim for women, who had no way of preventing pregnancies, and were often subjected to marital rape. Consequently, a growing number of women decided single life was preferable. Author Louisa May Alcott, for example, was determined not to marry. She was more fortunate than many single women in that her work as an author and a governess gave her economic autonomy.

As women gained autonomy, and were brought together by their jobs with other women, the beginnings of a number of disruptive social movements took place. Women, often single, were in the forefront of the abolitionist, temperance, union and suffragist movements. Traister’s discussion of that period was sprinkled with the names of single women who became active in those movements, some well-known, like Susan B. Anthony and Jane Addams, and others obscure, such as Elizabeth Penney, who advocated for equal pay for women in 1869, and Margaret Haley, head of a teachers’ union in Chicago who realized she could increase the power of her union by working with an all-male union.

There was, Traister said, “Increasing recognition of how marriage kept women from activism.”

The second half of the 19th century also saw the rise of women’s colleges, and as a result, moves by previously all-male colleges to begin accepting women.

Sadly, Traister said, the increased activism of women led to a backlash in the early to mid-20th century. In the early 20th century, at the height of the eugenics movement, Teddy Roosevelt gave several speeches in which he urged middle-class white women to get married and reproduce in order to preserve the white race. As the century wore on, women’s magazines began to focus on issues like dating and early marriage. By the 1960s, 60 percent of women were dropping out of college early to marry.

The impact of some of the social changes during that period on blacks was strikingly different. The mechanisms which helped create the white middle class, such as the federal highway system, the GI Bill and suburban housing developments, had the effect, whether intended or not, of preventing blacks from moving into the middle class, so while white marriage rates went up, the rate of black marriage, which was high following emancipation of slaves, dropped.

Then came Betty Friedan’s “The Feminine Mystique” in 1963, and the Moynihan Report on the black family in 1969, leading to renewed social activism in the late 20th and early 21st centuries.

Meanwhile, forces such as advances in and legalization of contraception, Title 9 of the Civil Rights Act, and laws giving women access to credit helped get “us to where we are now,” where 46 percent of adults under 34 in this country have never been married.

Yet, Traister said, we still do not have policies that support single women – policies like paid family leave and subsidized day care -- with the result that single women in disproportionate numbers still live below the poverty line.