In fact, during the next half century, nearly one of every four new state residents will live in Utah County — three quarters of them from births, according to the projections.
"We see a shift of population south, a shift of political power south, and shifting some economic activity south," said Natalie Gochnour, director of the institute.
The rising political clout of Utah County already can be seen. Gov. Gary Herbert, a former county commissioner, is the first governor from the county in generations. And three of the state's six-member congressional delegation have, until the recent resignation of Rep. Jason Chaffetz, been Utah County residents (including Sen. Mike Lee and Rep. Mia Love).
The shift comes as vacant land for new housing in Salt Lake and Davis counties is expected essentially to disappear in that time, and more families make their households in Utah County. Salt Lake County is still expected to continue as the economic heart of the state, with 40 percent of its jobs in 2065, making for some long commutes from elsewhere.
Still, Utah County is projected to add 576,000 jobs and boost its share of the state's employment from 17 percent to 24 percent by 2065.
With coming changes, don't expect Utah County to remain the bastion of conservative politics where all major officeholders now are Republicans, predicts Gochnour.
"Utah County is going to become much more like Salt Lake County over the next 50 years," she said. Salt Lake County — especially Salt Lake City — is the last stronghold of Democrats in the state.
Utah County "will become more diverse" because of people moving in, Perlich added. While most of its growth will be from births, she said many of those children will be to new move-ins who bring in outside characteristics.
Utah County Commission Chairman Bill Lee said it still may be a toss-up on how politics will change. He noted that while Salt Lake County recently has seen its percentage of Mormons decrease, that percentage climbed in Utah County — and members of The Church of Jesus Christ of Latter-day Saints tend to be more conservative.
Still, greater diversification "is going to come," Lee said during a roundtable discussion of the projections.
Gochnour said northern Utah County — around its new "Silicon Slopes" technology center — should see much more diversification in its population than will southern Utah County.
Lee said the projections — and how to handle all the growth — "could be fearful or really exciting." For example, he said, his county will need some major transportation projects, and long-range plans include major upgrades at the Provo airport and, possibly, even a bridge across Utah Lake.
Ted Knowlton, deputy director of the Wasatch Front Regional Council, said projections show that Salt Lake and Davis counties "are basically going to run out of fresh tracts of vacant land," which will make it "more difficult to do traditional road widenings" and may lead to more dependence on mass transit.
He said it will also change development patterns and likely lead to such changes as smaller lot sizes.
Quick growth statewide will also reinforce the need to conserve water, said Todd Adams, deputy director of the Utah Division of Water Resources. Still, he said, 82 percent of water in the state is now used for agriculture, and much of that may shift to municipal use as more and more farmland gives way to housing.
Other key findings:
• Utah's population is projected to essentially double, from 3 million now to 5.8 million in 2065.
• Statewide growth rates are projected to slow in the next 50 years, but still exceed national growth rates.
"For the foreseeable future, Utah does retain the signature demographic as the heartland of the Mormon culture region," Perlich said. "We will, for the foreseeable future, have the highest fertility rate in the nation; among the long life expectancies; larger families; and younger populations."
• In 2065, life expectancy in Utah is projected to be 86.3 for women and 85.2 for men. That is an increase of four years for women and six for men.
• Utah's median age is projected to increase by 7.5 years, rising from 30.7 years now to 38.3 years. That is a result of declining fertility and climbing life expectancy.
• The share of Utah's population age 65 and older is projected to double, from 10.2 percent of the population now to 20.3 percent in 2065.
• The school-age population, ages 5 to 17, is projected to swell by nearly 1 million by 2065, but comprise a smaller share of the population — dropping from 22.3 percent to 17.1 percent.
Sydnee Dickson, state superintendent of public instruction, said that will create constant demand for more education money and more teachers to keep pace with growth.
• The number of households is projected to grow steadily, but average household size is to decrease from 2.99 now to 2.57 in 2065.
"The projected acceleration of population and household growth will increase demand and prices in the housing market over the next few years," said Jim Wood, Ivory-Boyer senior fellow at the policy institute.
• Stable employment growth is expected. The fastest growing industries are projected to be construction, professional and scientific service, health care, education and arts, entertainment and recreation.
• Washington County is projected to have the most rapid growth among all counties: a 229 percent leap, from 155,000 resident to 354,000. It would become the state's fourth most populous, bypassing Weber County.
• Counties that ring the Wasatch Front are expected to see rapid growth, essentially expanding and becoming part of that vast metro area. Wasatch, Juab, Morgan and Tooele counties are all expected to more than double in population.
• All counties in the state are expected to grow in the next 50 years. Utah County will have the largest growth, adding more than 1 million new residents.