ST. LOUIS – A large group of well-meaning officials from several states have a message for you and your family: Go take a hike.

They’re urging moms and dads to take their kids away from the television and go outside for some fresh air as part of “Take a Child Outside” week from Sept. 24-30.

The special week began last year in North Carolina, and has now spread throughout much of the U.S. About 250 organizations in the U.S. and Canada are taking part this year.

Do children really need a themed week to encourage them to play outside?

Supporters say it certainly could help. With child obesity on the rise and children spending more time playing electronic games or surfing the Internet, supporters of the effort are extolling the virtues of getting out of the house.

“There’s just a disconnect with the natural world around you,” said Sue Holst, a spokeswoman for Missouri’s Department of Natural Resources, which oversees the state parks. “Today’s children do not seem to have the same connection to the outdoors.”

Liz Baird, director of school programs with the North Carolina Museum of Natural Sciences in Raleigh, agrees: “When I was a kid, you had to come inside when the street lights came on.”

Baird, who came up with the idea of “Take a Child Outside” week, said now parents often have to tell their children they must go outside for 30 minutes.

Baird read Richard Louv’s book “Last Child in the Woods,” about the disconnection between children and nature, and invited him to visit the museum where she worked.

“I struggled with what the museum could do, because we’re indoors,” she said. “We’re a fake outdoors!”

But she said the museum drew from its knowledge of educating and activities for children.

The effort comes at a time when the Centers for Disease Control and Prevention says 17 percent of U.S. youngsters are obese and millions more are overweight. Obesity can lead to diabetes, high blood pressure and cholesterol, sleep problems and other disorders.

Missouri’s Department of Natural Resources is suggesting that parents take a hike with their children, go fishing, take a float trip and camp together — or even just sit at a picnic table and watch kids explore. The department also has a year-round effort called “Get Out and Play” to support more free time for children outside.

Attendance is down about 2 million visitors at Missouri’s state parks, from about 18 million annually in 2004 to 16 million in 2007. Park officials can’t say conclusively why that is — rising gas prices may play a role — but they think families also need to be reminded of what parks offer and the benefits of outdoor play.

Child development specialist Jane Kostelc she hadn’t previously heard of “Take a Child Outside” week but thought it was a good idea.

“There’s a different dimension to their development when they play outside,” she said. She works for the St. Louis-based Parents as Teachers National Center, an international parent support and educational program.

Outdoor play allows for freedom of movement and more vigorous movement. It also sparks creativity and observation skills, as children use outdoor materials in their play and take in the changing world around them, Kostelc said.

Baird acknowledged it may be a sign of the times that promotions are needed to encourage outdoor play, but she hopes families will spend more time in the natural world the rest of the year.

“I always end by saying my honest hope for the week is that one day it won’t be needed,” she said.