Half of the people in North America's largest cities do not have a better half, says new research -- a growing trend that represents the biggest demographic change since the Baby Boom.

Renowned New York University sociology professor Eric Klinenberg's recent book "Going Solo: The Extraordinary Rise and Surprising Appeal of Living Alone" has caused a stir for its enlightening exploration of the phenomenon of staying single and living alone.

"When I started the book, I had no idea how prevalent it had become," Klinenberg told CTV's National Affairs on Tuesday. "Until the 1950s you couldn't find a single society in human history that had sustained large numbers of people living alone for long periods of time. That has transformed dramatically since then."

In the most prosperous American cities -- Atlanta, Denver, Seattle, San Francisco, New York, Washington and Minneapolis -- at least 40 per cent of household consist of a single person.

Statistics Canada has found the same trend taking hold here. In the 2006 census, single Canadians outnumbered married Canadians for the first time, with 52 per cent of Canadians never having been married.

In Canada's largest cities, the number of singles is even higher:

• Vancouver -- 58 per cent
• Toronto -- 53 per cent
• Edmonton -- 55 per cent
• Montreal -- 66 per cent
• Victoria -- 70 per cent

In "Going Solo," Klinenberg found that "Singletons" (his word), while still stigmatized by society, are growing in economic and political power. Yet only online dating sites directly target singles with their advertising.

He also found that single people are more likely than married people to belong to social groups, give back to their community and spend their disposable income on the fun stuff such as bars, restaurants and the theatre.

"People who live alone are more likely to be social," Klinenberg said. "This was a big surprise to me."

In a recent New York Times article, Klinenberg wrote: "Living alone comports with modern values. It promotes freedom, personal control and self-realization — all prized aspects of contemporary life."

Klinenberg also says that the vast majority of those staying single are doing so because they want to, a trend which was spotlighted by Kate Bolick's "All the Single Ladies" in The Atlantic last year.

But Andrea Mrozek from the Institute for Marriage and Family Canada, which was established by the evangelical Christian group, Focus on the Family Canada, says most young people still want to get married.

"The reality may look different than that, but marriage is still an aspiration for so many people," she said on National Affairs. "I don't think it's negative or positive if people are living alone, but there are benefits to marriage."

Klinenberg, a married man himself, says the majority of people would like to get married, but in modern society people are placing a greater emphasis on happiness in marriage and are waiting longer to find the right person.

"They want to make sure they are making the right choice and are investing in themselves and careers, and establishing their own security," he said. "People who wait a while to get married are more likely to stay married."

Mrozek says marriage is still the best place to raise children and will remain the ideal.

"Marriage is difficult and isn't a walk in the park, but we don't have evidence that leaving a low-conflict marriage makes people happier," she said.