At visiting day at my sons’ day camp in Westchester this week, I struggled to tell the difference between the counselors and the mothers. The counselors were wearing bathing suits, but many of the mothers weren’t wearing much more. They were sporting this season’s short shorts, skimpy tank tops, gold hoop earrings, and summery flip-flops.

They didn’t just look young. They were young. They were wearing shimmery lip gloss, had their hair in ponytails, and were effortlessly balancing the act of sitting on the grass watching the campers play whiffleball and sprinting after their younger children.

Now, as a city mom, I am used to telling the difference between generations. Except that in our urban playground, I’ve become quite skilled at distinguishing between mothers and grandmothers. One of the most memorably embarrassing moments I’ve witnessed occurred early in the school year, when the guard at my sons’ school asked a friend of mine if she was picking up her grandchildren. It was not a pleasant moment.

“My grandchildren?” she fumed. I eyed my friend, well into her 40s, dressed in a silk blouse and skirt, and could understand how the guard had made the mistake. She didn’t look much younger than some of the expertly nipped and tucked grandmothers that do pickup duty once a week, sometimes arriving at the schools in their sweats, after a tough personal training session.

Long gone are the days when a couple in their mid-40s pushing a double stroller down Broadway causes any heads to turn. To make headlines, in fact, you’ve got to be a 67-year-old Romanian woman giving birth for the first time.

According to the U.S. Census Bureau, the more educated and ambitious a woman, the more likely it is that she will delay marriage and children. So it is no surprise that city moms, more focused on their careers, are on average older than suburban moms.

“I grew up in Westchester, and almost all my friends from high school are married with a few kids,” said one of the mothers, 33, that I spoke to at the camp’s visiting day. “The women I know around here – they got married in their 20s, worked for a little bit, and pretty quickly had kids. If they could afford it, they stopped working. And to be honest, I don’t think very many of them feel upset about not having had killer careers. I imagine it’s a very different profile from a lot of the mothers living in the city,” she added.

A friend of mine whose child is starting nursery school in TriBeCa said that almost all the parents interested in the school are in their late 30s and early 40s. “They are the ones who focused on their careers first and are now having kids. Both spouses made a lot of money, bought these great lofts, and can afford to raise their kids in the city,” she said.

But other anecdotal evidence suggests that perhaps the pendulum is beginning to swing the other way, and that even in the city fewer women are delaying motherhood for as long as they used to.

“We still get plenty of women in their 40s who are shocked to learn that their eggs are no longer viable,” an obstetrician in private practice on the Upper East Side told me. “But we are also seeing more and more women in their mid- and late 20s having babies.”

The feminist dream from the 1970s of having a successful career and family is still alive and kicking in New York. It’s just no longer defined as having a successful career and family at the same time.

Data from the U.S. Census Bureau suggests that fewer women are trying to do it all at once. In 2002, 55% of women with infants under a year old were in the labor force, down from 59% in 1998. The greatest decline occurred among white mothers over 30 with at least some college education.

“We used to be inundated with twin applications. The parents were in their 40s, both spouses had successful careers, they had waited until the last minute to have kids,” one admissions director at an uptown nursery school said. “We still see lots of that, but we also see more and more younger mothers – just as educated – but most are home with the kids. It will be interesting to see what those women do when their kids go off to college.”

One mother I spoke to at camp visiting day said she has given a lot of thought as to what she’ll do after raising her children. “I’m so happy that I’ll still be really young when my kids are in college. There are trips I want to take and things I want to do with my husband. I have my Master’s in social work. I want to do something that uses the degree. I won’t even be 50 years old then,” she said.

If 50 is the new 40, she’ll have lots of time for the trips and career. And if 60 is the new 50, the TriBeCa parents will have plenty of time for traveling, too. As for picking up their grandchildren, though, they might not be so easily confused with the parents. But with the right personal trainer and plastic surgeon, you never know.