Maricopa County added more people last year than any other county in the nation, but it was neighboring Pinal County that posted the fastest growth rate in the state, a beneficiary of overflow from its neighbor to the north.

The Census Bureau said in a late March population report that Arizona added 113,506 people from July 2015 to July 2016, with 81,360 of those people moving to Maricopa County – more than 222 per day to boost the county’s population to 4.2 million.

But Maricopa County’s 2 percent growth rate trailed Pinal County, which added 12,320 people for a 3 percent jump during the year, the fastest growth rate in the state.

As a bedroom community for Maricopa County, where many of its residents work, growth in Pinal county “is not unexpected right now,” said Joe Pyritz, a spokesman for the county government. The county had an estimated 418,540 residents in July, according to the Census Bureau.

“We have a lot of housing that is on the more inexpensive side. With that, people will work in Maricopa County and live in Pinal County,” he said.

The median price of Pinal County homes listed on the real estate appraisal site Zillow is around $199,000, almost $100,000 less than the median price Zillow listed in Maricopa County.

Most counties in Arizona have seen steady growth in recent years, and the latest Census report showed that trend continued last year. Only Graham, Santa Cruz and Cochise counties posted population losses in the same period.

“Population has been moving south and west, and we are in the Southwest,” said Arizona State Demographer Jim Chang. “Maricopa obviously is the largest county in Arizona, and the economic center of Arizona. It attracts the largest portion of people coming to Arizona.”

And Pinal has been the beneficiary of that growth as it spills over, Chang said.

Not every county has been so lucky.

While Pinal and Maricopa counties saw 11 percent population gains from 2010 to 2016, according to the Census, border counties Santa Cruz and Cochise lost 3 and 4.6 percent of their residents, respectively.

Cochise County, home to Bisbee and Fort Huachuca, has seen its population drop to 125,770, a drop of 5,586 people over the past six years.

“We’re not really sending up alarm bells,” said Lisa Marra, a spokeswoman for the Cochise County Board of Supervisors.

She said the county’s biggest employer is the Army’s Fort Huachuca, which has seen troop decreases over recent years, in part due to defense sequestration putting a hard cap on military spending.

Chang said changes on the base are bound to be felt in the county.

“It’s military personnel, and their families, and when we lose some of those we lose business,” he said. “It’s a ripple effect.”

Marra said the county has an older demographic – one in five is age 65 or older – which is not conducive to population growth. The county government is working to attract younger people by trumpeting the region’s “good air, low crime and healthy communities.”

“We have a lot of opportunities for growth,” Marra said. “Down here, in a smaller community, you can really make an impact.”

While Maricopa County saw the nation’s biggest numerical increase in residents, San Juan County, Utah, had the fastest rate of growth at around 7.6 percent.

The biggest losers in the nation were Cook County, Illinois, which lost 21,324 residents, and Eureka County, Nevada, which saw its population decline by 5.43 percent over the year, according to the March 23 report from the Census.

By Arren Kimbel-Sannit, Cronkite News