All the Single Ladies: Unmarried Women and the Rise of an Independent Nation. By Rebecca Traister. Simon & Schuster; 352 pages; $27 and £16.99.

Enter Helen: Helen Gurley Brown and the Rise of the Modern Single Woman. By Brooke Hauser. Harper; 480 pages; $28.99 and £20.

Spinster. By Kate Bolick.Crown; 336 pages; $26.

“I MARRIED for the first time at 37. I got the man I wanted,” crowed Helen Gurley Brown on the first page of “Sex and the Single Girl”, a runaway bestseller in 1962. She snagged a brainy, sexy, fabulously successful beau despite being neither “bosomy” nor brilliant, she added. But by the time they met, she was worldly enough to beguile him, having spent almost two decades living by her wits as a single woman, sharpening her skills in the office and the bedroom. “Marriage is insurance for the worst years of your life,” she quipped. “During your best years you don’t need a husband.”

As Brooke Hauser writes in “Enter Helen”, a colourful new biography, Brown cunningly sold a brand of empowerment in terms that would please men. As editor of Cosmopolitan from 1965 to 1997, she transformed a family-friendly magazine into a titillating and wildly successful glossy for women not yet ready to be wives or mothers, but craving male attention all the same. Feminists balked at the busty cover-girls and articles about losing weight and wearing false eyelashes to bed, but countless women also learned how to avoid pregnancy and secure a loan. Before Betty Friedan exploded the myth of the happy housewife in “The Feminine Mystique” in 1963, Brown was already telling women to live a little before settling down.

Brown was prescient. As Rebecca Traister writes in “All the Single Ladies”, on the rise of single women in America, women are waiting longer to wed than ever, and many are choosing not to do so at all. The freedom to pursue high-powered careers and sexually diverse lives without fear of pregnancy or stigma has turned marriage into a choice, not destiny. By 2009 nearly half of all American adults younger than 34 had never married, a rise of 12 percentage points in less than a decade. Unmarried women outnumber married ones for the first time ever.

Single women are reshaping politics. As women tend to worry more about reproductive rights and fair pay, they have favoured Democrats for president since 1988. But the overall women’s vote hides a divide: in 2012 Mitt Romney narrowly carried married women, while the unmarried rushed to Barack Obama in their millions, giving him a 36-point margin. Single women cast almost a quarter of the votes, nearly guaranteeing his re-election. They may be even more important this year: a recent poll shows Hillary Clinton, the likely Democratic nominee, leading Donald Trump, the Republican front-runner, by 52 percentage points among unmarried women.

Delaying marriage is also having economic effects: women aged 25 to 34 are the first generation to start their careers near parity with men, earning 93% of men’s wages. Single women now buy homes at greater rates than single men, a big step in independent wealth-building.

These trends have some conservatives fretting about the decline of the family, but Ms Traister convincingly argues that “independent female adulthood” has been good for marriage. The divorce rate rocketed in the 1970s and 1980s, as women who had rushed into unhappy marriages discovered they could make their own way. The boom in divorce encouraged many in the next generation to abstain from marriage rather than enter a flawed one. Now that marriage is simply one option among many, fewer women are exchanging vows, but those that do tend to be in happier, more co-operative relationships.

The divorce rate, now falling, has plunged fastest among those who stay single longest. Despite the stereotype that high-achieving women are doomed to spinsterhood, the truth is that these women are now the most likely to tie the knot, and can afford to hold out for the right match. Ms Traister says that her own successful work as a journalist in New York made it easy for her to feel fulfilled through her early 30s, until she met and fell in love with the man she would marry: “I wound up happily married because I lived in an era in which I could be happily single.” More demanding women are also making men evolve; the number of stay-at-home dads in America almost doubled in the first decade of this century.

Not all women are celebrating. For some, singlehood is less a choice than bad luck. Outside big cities, women who are unmarried into their late 30s are often pitied. For those who hope to become mothers, biology imposes harsh deadlines—though breakthroughs in fertility treatments have raised the number of women giving birth after age 35 by 64% between 1990 and 2008.

In particular, poor single women face a different landscape. Not all are unmarried by choice: America’s high incarceration rate has shrunk their pool of men. Single parenthood is strongly correlated with poverty. Conservatives duly push marriage as the antidote: the federal government has spent almost a billion dollars on pro-marriage programmes, to little avail. Ms Traister stresses education, housing and child care instead, noting that in northern European countries, marriage rates have plunged without poverty increasing.

Ms Traister is right to cheer the advances that have created this new era. But with choice comes uncertainty, and this is the subject of “Spinster”, Kate Bolick’s often lyrical bestselling memoir about making a life on her own, now in paperback. Some readers will disagree with her opening claim that whom and when to wed are questions that continue to “define every woman’s existence”. But she is right that mentors for the new single life are hard to find. Her own late mother, like so many in her generation, married young and set aside her ambitions to raise children.

Now 43, Ms Bolick has spent around two decades casting about for inspiring templates of modern-day spinsterhood. She offers five “awakeners”, including Edith Wharton, Edna St Vincent Millay and Charlotte Perkins Gilman. They show Ms Bolick “how to think beyond the marriage plot” at pivotal moments of her life, as she cycles in and out of romantic dalliances and writing projects, largely in New York.

Some have carped that for a book about life on her own, Ms Bolick seems to suffer no shortage of boyfriends (her publisher, keen to make clear that she is a “spinster” by choice, put a picture of the beautiful author on the cover). Others have grumbled that her “awakeners” are all relatively fortunate white women who marry at some stage. But this misses the point. Ms Bolick’s is a personal story of the pleasures and challenges of being a woman at a time of changing rules and seemingly endless possibilities. Helen Gurley Brown once promised women that they “could have it all”. Women today know better. But it is surely good to have so many more options to choose from.