For millions of young Americans, the pandemic has been a time machine back to the early aughts.

By July 2020, 52% of 18 to 29 years olds, or 26.6 million adults, were now residing with a parent, according to a new Pew Research Center analysis — the highest number since the Great Depression.

Teenager's bedroom during quarantine times

In New York, some 300,000 left the city. Many of those people found themselves living in time capsules: lovingly preserved childhood bedrooms, plastered in posters and magazine cut-outs of boy bands. (iStock)

In New York, some 300,000 left the city. Many of those people found themselves living in time capsules: lovingly preserved childhood bedrooms, plastered in posters and magazine cut-outs of boy bands and James Cameron blockbusters, and tricked out with décor from the Myspace era.

Many are still there.

Jess Cohen, 39, was one of them. She left her Manhattan apartment during the pandemic to move back in with her family in Fresh Meadows, Queens. Her modest bedroom hadn’t changed since high school, two decades ago.

A "Titanic" poster, a Barbie-sized Kate Winslet doll, the sign-in board from her Sweet Sixteen, stuffed animals and glass knickknacks from a school formal where just as she had left them.

The girlish pink walls were the cherry on top of what feels like a "Blossom" meets "Clarissa Explains It All" retrospective.

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"I originally thought I would only stay for a couple of weeks, but with COVID still out of control, I just stayed, ‘Titanic’ posters and everything!" Cohen, who is a public-school teacher leading class remotely, said. "Thank goodness for virtual backgrounds on Zoom because teaching would be super embarrassing without them."

Save for some nicer bamboo bedding that she brought with her, Cohen hasn’t updated her childhood bedroom at all.

"Once I have to return to my job in person I am definitely going back to my apartment, so updates didn’t really seem worth the effort," she said. "Plus, the nostalgia is nice, reminds me of a simpler time!"

But "adulting" in one’s childhood bedroom is more of a mixed bag for most, and it’s spurring creative renovations.

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When Deanna Kugler Gallucci, 31, a PR pro, and her husband Bryan, 32, a radio producer, gave birth to their pandemic baby last July, her parents urged them to move back into her childhood room in Massapequa, Long Island.

"My parents begged us, in a light-hearted but truly guilt-trip parenting sort of way," said Gallucci. The experience was "nostalgic, chaotic, overwhelming, rewarding and fun," she added.  

While the furniture and décor had changed over the years, artifacts had remained trapped in time.

There were glow-in-the-dark stars on the ceiling, a poster from Rome, Precious Moments statues, including one which holds a picture of her on her first communion, and "Laguna Beach" DVDs.

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They got to work reorganizing the rooms with a dark cherry sleigh bed with a matching dresser and nightstand Gallucci picked up in college, a grey couch from their Manhattan apartment and even an oh-so-adult Peloton.

They updated nearly every detail in the room, from the floors (new rugs) to the walls (new curtains and décor). But one staple of a teenage room hasn’t changed: the overflowing laundry basket.

"There’s always laundry to be done and put away, which takes days. I hate laundry," she said.

This content continues in the New York Post.