COEUR d'ALENE - The sign welcoming travelers to Coeur d'Alene saying pop. 34,514 will need to be replaced or repainted.

Actually, many signs across the state will.

Idaho's populations grew by 21.1 percent from April 2000 to April 2010 according to initial 2010 Census data released Tuesday - the fourth biggest jump in the nation.

While the growth hasn't yet been pinpointed to individual cities, the 273,629-person bump from the 2000 Census boosts Idaho's total to 1,567,582 residents.

Overall, the Gem State ranks 40th in population. But the jump more than doubled the national rate of 9.7 percent.

"It doesn't surprise me," said Gary Clark, retired, who moved to the area with his wife, Colleen, from Yuma, Ariz., 14 months ago for the scenery and pace of life. "It worries me. I'm a hypocrite - I don't want to be - but I don't want anyone else moving here."

The state didn't gain an extra seat in the U.S. House of Representatives, but nearby Nevada, Utah and Washington will each gain an extra member of Congress. The West was the second biggest regional gainer with 8,747,621 more people, behind only the South's 14,318,924 person addition.

Nevada added the most people as a percentage of its 2000 Census count at 35.1 percent with a population of 2.7 million. California ranked as the most populated at 37,253,956, a growth of 10 percent.

The nation's new number sits at 308,745,538.

Locally, Idaho's and Washington's jumps could mean that the Coeur d'Alene and Spokane Metropolitan Statistical Area designations could combine into one. MSA's are statistical population density breakdowns for an area with close economic ties throughout the area and used for U.S. government agencies for statistical purposes only.

Currently, Coeur d'Alene and Spokane each have their own.

The Census won't be releasing numbers on the core-based statistical areas until November of 2011, and they won't be updating the designations until July 2013.

But with 500,000 people in the region, combination could be in the future, said Ryan Stewart, Kootenai Metropolitan Planning Organization senior transportation planner.

The two cities likely won't combine regional planning organizations, however, and therefore won't need to compete for federal funding on projects such as transportation.

"We're following it closely, it's too early to tell yet on what the impact could have," Stewart said. "It could be more funding, but we don't know for sure."

Coeur d'Alene's planning department estimates the city population around 46,000. The city has been growing at a 3 percent yearly rate since 2000. Idaho's 21.1 percent increase is down compared to the previous count. From 1990 to 2000 Idaho grew at a 28.5 percent rate. The state's population has doubled in the last 30 years.

Kellogg native Ryan Sheppard, 36, said he has noticed the increase in people since he was a kid in the Silver Valley.

"You see a lot more people out camping, and using the resources," he said Tuesday. "It surprises me because economic-wise, there's not much more, but people are still moving to the area. Hopefully, companies move with them."

Idaho remains one of the least dense states in the nation, ranked 46 out of 51 (including Washington, D.C.). In 2010, 19 Idahoans were measured for each square mile of the state. The national average is 87 people per square mile.

This decade marks the first time in U.S history that the West, as a region, counts as more populous than the Midwest.

Wyoming was the least populous with 563,626, and the state that gained the most numerically since the 2000 Census was Texas, up 4,293,741 to 25,145,561.

A key component, and a requirement by law, of the decennial Census is apportionment changes in the U.S. House of Representatives based on population shifts. Each member of the House represents an average of 710,800 people.

States losing representatives are Illinois, Iowa, Louisiana, Massachusetts, Michigan, Missouri, New Jersey, New York, Ohio, and Pennsylvania.

President Barack Obama will transmit the apportionment counts to the 112th Congress during the first week of its first regular session in January. The reapportioned Congress will be the 113th, which convenes in January 2013.