Butler County’s population continues to grow with most of that growth in the southwest corner of the county, according to data recently released by the U.S. Census Bureau.

An official census is done every 10 years, but the bureau does annual estimates broken down by state, county and municipality.

As of July 1, 2015, the county’s population was estimated at 186,818, an increase of 875 from the previous year’s mark of 185,943.

The two municipalities with the largest increases were Cranberry and Adams townships.

Adams increased by 282, from 12,930 to 13,212, and Cranberry increased by 285, from 30,173 to 30,458.

Jackson Township increased by 105 from 3,594 to 3,699.

There also were increases by smaller amounts in Buffalo, Forward, Franklin and Middlesex townships and Connoquenessing borough.

Elsewhere in the county, most municipalities stayed close to the same or had a decrease. For example, Butler decreased 82 from 13,371 to 13,289, and Butler Township decreased by 77 from 16,880 to 16,803.

Officials said the increases in the southwestern townships are expected given the continued residential and business growth there.

Cranberry manager Jerry Andree said the numbers are not surprising. The township estimates its population through building permits and has figures similar to the census bureau’s.

Continued residential and commercial development in the township explains the trend of growth.

“The economy is great here in southern Butler County,” Andree said.

The latest population figures are only a couple hundred behind what had been forecast by officials and community volunteers who developed the Cranberry Plan, Andree said.

Township officials anticipate the population to be about 52,000 people by 2030. The plan includes necessary infrastructure improvements to accommodate that level of growth.

Gary Peaco, code enforcement officer for Adams Township, said the township has about 190 new residential units being built each year, most of which are houses.

With more land available for development and a healthy real estate market, that trend is expected to continue for the next several years, he said.

Jim Boltz, executive director of the Pittsburgh North Regional Chamber, said the growth is not surprising given the presence of Interstate 79.

“I think the biggest reason is accessibility. You have that Cranberry, Jackson corridor that is convenient to everything in the Pittsburgh area,” he said.

Boltz said that commercial development has attracted residential development and vice-versa, giving the area momentum.

“It’s like an upward spiral. One continues to drive the other,” he said.

Some of the new residents likely have moved to the county from elsewhere in the region, while others are coming from elsewhere in the country or from abroad to work in the medical field or at businesses like Westinghouse, Boltz said.

“There is a good blend of people moving into the area,” he said.

The census estimates are created by checking births, deaths and migration. The biggest indication of migration is through housing numbers, according to the census bureau’s website.

The bureau looks at building permits, mobile home shipments and estimates of nonpermitted construction and housing loss.