Change is constant in St. George, by far the nation's fastest growing metropolitan area.

"We are just trying to deal with it the best we can," said Mayor Daniel McArthur.

A new Census Bureau report released today shows the population of St. George and its suburbs has grown by nearly 40 percent since 2000.

Second place? That belongs to Greeley, Colo., which has seen a 31 percent population spike since the start of this decade.

The report illustrates a widespread trend, where people are moving to warmer areas in the South or the West, many to retirement hot spots. Other top 10 growing metro areas include Las Vegas, Phoenix and two Florida locales.

Utah had another top 10 finisher - Provo and Orem came in as the sixth fastest growing metro area, with a 26 percent growth rate. Metro areas have at least 100,000 people. Heber and Cedar City made the top 10 fastest growing micropolitan areas, or places with 10,000 to 50,000 residents.

Robert Spendlove, the state's chief economist, said the fast growing areas are "definitely a reflection that Utah is a very attractive place to live and work."

It's also a reflection that Utah is still a cheaper place to live than many of its neighboring states.

Demographer Pam Perlich from the University of Utah says age data tells much of the story. The St. George population is one of the state's oldest, while Provo is one of the youngest.

On a percentage basis, the St. George metro area, which includes all of Washington County, has twice as many elderly residents as Salt Lake County or Utah County. Perlich said this shows many of the people flooding into St. George are retirees.

In contrast, Provo and Orem have far more college-age residents per capita, in part because of the expansion of Utah Valley University and the continued growth of Brigham Young University. Those college-age Utahns are also having lots of kids.

"Babies don't come with income, but the retired folks do," said Perlich, describing the hot growth in the St. George economy.

Low unemployment rates and lack of cheap housing make it difficult for companies to attract workers.

These business complications, along with the need for greater transportation and new utilities, have led to a comprehensive planning exercise known as Vision Dixie, which is a collaboration between Washington County government and the nonprofit planning agency Envision Utah.

In a series of workshops, residents are asked to create maps showing housing, business development and new transportation routes. Their input will ultimately lead to one vision, and the one constant is a population that continues to expand.

Such growth is not new for the St. George area. The county population has increased by at least 6 percent annually since the late 1960s. But the effect is magnified over time.

Back in the late 1960s, a little more than 11,000 people lived in the St. George area. Now, more than 126,000 people call Dixie home.

By 2035, county and city leaders expect the population to balloon to 400,000.

"We are trying to be proactive about it," said Washington County Commissioner James Eardley, who is also leading the Vision Dixie effort.

The group will release four possible growth plans, including new roadways, public transportation, dense housing and mixed-use developments, by the beginning of May.

Eardley hopes the models will become the basis for a revised Washington County land use bill that Sen. Bob Bennett and Rep. Jim Matheson will spearhead in Congress.

The original version of the bill came under fire from environmental groups because it called for the sale of up to 25,000 acres of federal lands. The money would stay in the county for conservation projects.

The Southern Utah Wilderness Alliance and the Sierra Club have fought against that bill.

Eardley said he expects Bennett and Matheson to introduce a new version in August.

Matheson said he expects the Vision Dixie process to defuse much of the criticism of the land use bill, meant to create a plan to help the county handle its burgeoning population.

More than this, Eardley hopes that St. George and other cities will use the plan as they prepare to cope with the hundreds of thousands of new Utahns to come.

mcanham@sltrib.com