In the middle of the 1970s, it seems, Americans decided it was time for recess.

Vietnam and Watergate had passed. It was party time.

That's the backdrop for CBS' "Swingtown." It starts in the summer of 1976, as Chicago suburbanites ponder the Bicentennial, the election, the Olympics and talk of a new morality.

The protest era has left aftershocks, says "Swingtown" creator Mike Kelley. "Some of it had trickled into the culture and reached the mainstream."

People re-thought their lives, he says. "They were saying, 'What if we don't follow all the rules?' "

Now we see that through the eyes of Susan Miller.

"She had a daughter when she was 16 or 17," says Molly Parker, who plays her. "She never had the '60s experience; she didn't go to college. Her experiences are limited."

Moving to an upscale neighborhood with her husband and kids, she's astonished to meet a mate-swapping couple (Grant Show and Lana Parrilla). This is a new world.

In one way, "Swingtown" is about sex; in another, Parker says, it's about much more. "It's really about the swing of the whole culture."

Yes, sex dominated the discussion. In 1969, the popular movie "Bob & Carol & Ted & Alice" showed married couples considering swapping. In '72, "Open Marriage" was published; it included a brief chapter on sexual openness. In '76, the "Hite Report" on female sexuality was a best-seller.

It was a time for free spirits. In the week after the Bicentennial celebration, the No. 1 song on the Billboard chart was "Afternoon Delight." The No. 1 songs that fall included "Play That Funky Music," "Disco Duck" and "(Shake, Shake, Shake) Shake Your Booty."

That fall, cheery shows on ABC ("Happy Days," "Laverne & Shirley," "Charlie's Angels") moved to the top of the ratings. It was not a serious time.

Kelley was 8 that summer, a suburban kid in Winnetka, Ill. "My parents had unique friends and great parties," he says. "These fabulous couples would pass by."

His mother has assured him that his parents weren't swingers or swappers, he says. Still, he can't help guessing about the other people he saw.

That leads to "Swingtown," which he calls "more imagination than history."

He includes kids, wobbling at the edge of teendom. And he gives Parker a teen daughter who is already having sex with a boyfriend and dreamy thoughts about a teacher.

"As the show goes on, the daughter will be challenging her to be free," Parker says.

For Parker, acting is an ongoing history lesson. "Deadwood" had her owning a gold mine in the Old West; "Iron Jawed Angels" put her in the fight to get women the vote.

"I love doing period pieces," she says. Still, these women "haven't been able to fully explore their potential."

Now "Swingtown" has a time of huge changes — social, sexual, personal.

Kelley has spent his TV career on dramas that generally skip the big three — cops, lawyers and doctors — and focus on character. He worked on "Providence," "One Tree Hill," "The O.C." and "Jericho," then aimed "Swingtown" at cable.

Instead, Nina Tassler, the CBS programming chief, grabbed it. She knows the era, Kelley says; her cousin co-wrote "Open Marriage." Tassler was enthusiastic. "We're going to push the envelope with this show," she told reporters last July.

This isn't just about sex, she says. "It's about community and it's about a period ... when people were experimenting."

Some may or may not have been experimenting at the parties that young Mike Kelley saw. He can imagine, anyway.