Article Last Updated:11/15/2006 01:18:38 AM MST

Just 40 years ago, much of southern Salt Lake County was farmland, producing everything from fruit to hogs.

Now it is covered in big homes and overrun with young families.

And those four decades of growth have led to a historic milestone.

In 1966, Utah's entire population just topped 1 million. This year, Salt Lake County has reached that number, according to the state's leading demographer.

This is but one of the intriguing findings by the Utah Population Estimates Committee, which met Tuesday to cobble together state population figures.

These statisticians estimate that Salt Lake County's population as of July 1 was 996,000, and that number kept growing in the past five months.

"You can arguably say that Salt Lake County has already surpassed 1 million," said Robert Spendlove, the head demographer for the Governor's Office.

In less than two years, Utah County should reach a milestone of its own, topping 500,000.

The population committee's main finding is that Utah's dense urban core is getting even more crowded. The state population reached 2.6 million, about 68,000 more people than last year, which is like adding a city the size of St. George in just 12 months.

More than half of that growth came in Salt Lake and Utah counties, and a great number of the move-ins and births have taken place along the shared border of these two counties.

But once again, Washington County is growing even faster than the Wasatch Front.

Washington County, which includes St. George, saw a population jump of 6.1 percent last year, the only county that grew twice as fast as the state. And for Washington County, that is a slowdown.

Last year, the area grew 8.4 percent, making it one of the fastest-growing counties in the nation.

Kenneth Sizemore, who oversees the Five County Association of Governments based in St. George, attributes the slowdown to "market forces."

"The entire nation is seeing a softening in the housing mar- ket," said Sizemore, a member of the population committee.

The slowdown is good news for some public officials, who are worried the growth could outstrip their ability to handle the increased demand for roads, water and sewer lines.

"You do have some officials taking a breath," Sizemore said, though he noted that 6.1 percent is still high.

Utah as a whole grew faster last year - 3.2 percent in 2005 compared with 2.7 percent this year - but the state still remains one of the five fastest-growing states.

The state estimate is much higher than the estimate of the U.S. Census Bureau, and the gap may end in a legal dispute.

Utah could be the first state to ever challenge census estimates, Spendlove said.

But a decision, which would need the approval of Gov. Jon Huntsman Jr., will not happen until after the new census estimates are released next month.

Last year, the federal estimate was 78,000 people lower than the state estimate, which could mean less federal money for Utah programs.

The census estimate is based almost exclusively on IRS data, while the state estimate also includes school enrollments, housing permits and the LDS Church membership records in each county.

Spendlove said the census figures may underestimate the number of undocumented immigrants, among others.

In the past two years, the census has accepted 22 challenges to its city and county estimates.