Bar Nunn has grown at the fastest rate in Wyoming over the past seven years, almost doubling in size.

The town was second in the state behind Pinedale for percentage growth last year, growing from 1,523 people to 1,700 people, or 10.4 percent, according to U.S. Census Bureau data released today.

In 2000, the Natrona County town had only 936 people.

Town officials think Bar Nunn is actually larger than current census numbers.

"Our estimate is that we are well over 2,000," said Carol Pendley, Bar Nunn clerk and treasurer.

The town estimates its population differently than the Census Bureau. The recent figures from the agency are based on building permits and other housing unit data used to estimate population, whereas the town uses sewage accounts.

Pendley attributes the growth to the availability of property and affordable housing in Bar Nunn. Several subdivisions have been added in the past couple of years, and most houses cost less than $200,000.

"It's quiet. It's more of a rural setting. The lots are large, and there's more room to grow," Pendley said.

People move to Bar Nunn because they can't find places to live near their jobs in downtown Casper or in the mines in northeast Wyoming, Pendley said.

Bar Nunn used to be just a few houses, said Kim Rightmer, economic development coordinator for the Casper Area Economic Development Alliance. Now, the town is booming.

"Bar Nunn has changed so much in the last five or six years," said Rightmer, who has lived in Casper since 1987.

Casper is doing well with population growth, Rightmer said, because of the availability of jobs.

The city grew from 51,965 people in 2006 to 53,003 in 2007. Since 2000, the city has grown by almost 7 percent.

"It's nothing extraordinary," Rightmer said. "But it's a positive increase."

Energy companies, such as J.W. Williams Inc., have expanded in recent years, adding more high-paying jobs in Casper.

Growth improves quality of life, Rightmer said. It adds activities, jobs and options for health care and education.

It also creates a positive attitude among city government, businesses and residents.

Rightmer said there are a number of businesses exploring Casper, but couldn't name names.

"I'm not seeing this leveling out any time soon," Rightmer said about population growth. "I'm very optimistic it will continue."

Each city and town in Natrona County posted gains.

To the northeast, Gillette and Wright ranked among the top 20 in the state for percentage growth in 2007.

The energy and construction industries have made the county grow, said Ruth Benson, executive director of the Campbell County Economic Development Corp.

"The rest of the country's demand for energy has made our economy grow," she said. "One-third of the coal used for the nation's electricity comes from the county."

Also, construction of two new power plants has added hundreds of construction workers to the area. By next summer, Benson said, there will be more than 1,400 construction employees building the two facilities.

Gillette has grown 27 percent since 2000 to 25,031 people. Benson said the city has kept up with the growth, though affordable housing has been an issue.

She also reported a 0 percent vacancy rate for apartments in the area since 2005.

The growth has been fast, Benson admits, at "breakneck" speed the past couple of years.

Benson thinks 2008 numbers should show a slowing in growth.

"It's probably a healthier rate of growth," she said.

Contact reporter Allison Rupp at (307) 266-0534 or allison.rupp@trib.com.