Meanwhile, the new Census analysis also shows that Utah with its highest-in-the-nation birthrate finished second-lowest among the states behind Alaska for its percentage of residents older than 65, as older folks here are vastly outnumbered by kids.
But demographers say that is about to change.
"With life expectancy in Utah among the highest in the nation, we can expect that those age 85 and older actually will be our fastest-growing age group over the next 20 years," said University of Utah research economist Pam Perlich. Actually, that group grew at a fast rate over the past decade, too: up 42.5 percent, compared to Utah's overall growth rate of 23.8 percent.
But for now, seniors are still vastly outnumbered especially in West Jordan.
Not only is that city lowest in the nation for percentage of those age 65 and older, it is also lowest for percentage of those age 85 and older, at 0.4 percent (about three-fourths below the national average).
Two other Utah cities also stand out in national rankings. Provo had the fifth lowest percentage of those age 65 and older at 5.8 percent. West Valley City had the eighth lowest percentage of those age 85 and older at 0.5 percent.
Tom Burdett, West Jordan's development director, said it was once a farm town, but has boomed into a big suburban city of homes, offices and shopping. Its population grew from 4,221 in 1970 to 42,892 in 1990 to 103,712 in 2010.
"We have about 5 percent growth annually. That's a lot," he said. "The in-migration has almost all been young families" attracted to new affordable homes. He said seniors who lived in West Jordan all their lives are simply outnumbered by the young newcomers.
"There are still a lot of seniors, though," said Nancy Freeman, director of the West Jordan Senior Center. Despite the distinction of running a senior center in the U.S. city with the lowest percentage of seniors, she says, "We have about 1,000 people who come into our center every month for activities."
Mayor Johnson said the city is also working to attract more senior housing, and some projects for them have been built recently. "We welcome seniors. Personally, I think they have more time to volunteer, and they help the city."
Perlich said Census data show a sort of age segregation in the Salt Lake Valley. She said east-side areas such as Holladay, Millcreek and Cottonwood Heights have the state's oldest median ages, while cities on the west side are the youngest.
She said that is because housing tended to be more expensive in some of the areas with older populations, and more affordable housing on the west side. "Young families can't afford expensive housing. So the age segregation comes largely from the life cycle of those neighborhoods."
As the large post-World War II baby boom generation ages and life spans increase, Perlich said projections show the numbers of those older than 65 or even 85 will boom. It will create some interesting problems, too especially because the number of children in Utah is also expected to continue to boom.
"Under a variety of scenarios… by 2040 when the baby boomers are old, we end up with just as many old people per working person as the rest of the nation, but we have lots more kids," she said which may make supporting the old and young a challenge.
The data released Wednesday show Utah in 2010 had 249,462 people older than age 65, up 31.1 percent since 2000.
Utah had 30,991 residents older than age 85, up 42.5 percent in the decade.