The only states that grew faster were North Dakota home to a current energy-industry boom at 2.17 percent; Texas, 1.67 percent; and Wyoming, 1.60 percent. The District of Columbia also grew faster than Utah at 2.15 percent.
Utah's fast growth comes largely because "we have a unique demographic structure, largely based on LDS culture" that historically favored large families and helped improve health by avoiding vices such as tobacco, said David Stringfellow, senior economist with the Governor's Office of Planning and Budget.
The census said Utah had the highest birthrate in the nation in the year, estimated at 18 per 1,000 residents. It had the second-lowest death rate behind only Alaska at 5.2 per 1,000 residents. It helped Utah have a "natural increase" of 36,245 people.
Pam Perlich, senior research economist at the University of Utah, said while that trend results in part from the Mormon culture, much of it comes simply because Utah has so many young people, as shown by the state having the nation's lowest median age.
"The death rate goes up with age, so when you have a lot of young people it is lower," she said. "And birthrates are higher when you have a lot of young people, because they are the ones who have babies."
Utah has so many young people, Perlich said, that "even if we had the same fertility rate as the nation and even if we had the very same mortality rate as the nation, Utah would still have one of the highest rates of natural increase."
Stringfellow adds that "demography is destiny, so we're going to keep growing at a fast clip" for years to come.
That will occur, Perlich notes, even though the fertility rate among Utah women has been falling in recent years toward national averages. In fact, the census estimates that Utah births dropped by about 1,000 in the past year, compared to the previous year.
Utah's birthrate has been falling since 2008 as the recession hit, Perlich said. "Across the board, people are delaying having children or actually deciding to have fewer children for the duration, partly because of the economic conditions."
The census also estimated that Utah had a net in-migration (the difference between people moving in and those moving out) of 4,730 people in the year. Its rate for in-migration was in the middle of the states at No. 25.
"Our economy has been one of the top performers in the country, and that tends to draw migration" from people seeking work, Stringfellow said.
Census data said net migration from other states to Utah was essentially at zero, and that virtually all net migration to Utah resulted from international migration which includes returning LDS missionaries and college students along with new foreign workers.
Even while growing at a much faster clip than most states, Utah remains only 34th in population. California is the largest at 38 million, followed by Texas, 26.1 million; New York, 19.6 million; Florida, 19.3 million; and Illinois, 12.9 million.
Nationally, the U.S. population grew by 2.3 million to a total of 313.9 million. Only two states lost population in the year Rhode Island, down 0.03 percent, and Vermont, down 0.09 percent.
Fastest growing states, 2012
1. North Dakota • Up 2.17 percent
2. Texas • Up 1.67 percent
3. Wyoming • 1.60 percent
4. Utah • 1.45 percent
5. Nevada • 1.43 percent