The Allegheny County population — a number that has steadily ticked lower for most of the last 50 years — went up, according to a new report released by the U.S. Census Bureau.

“The amount of population growth isn’t large in itself, but this is still a unique region with more natural population decline, meaning more deaths than births, so the actual migration flow is larger than the numbers show,” said Chris Briem, regional economist at the University of Pittsburgh’s University Center for Social & Urban Research.

The report, the first since the official 2010 Census, measured slight population swells between April 1, 2010 and July 1, 2011, both in Allegheny County and Pittsburgh’s seven-county metropolitan area. During these months, the metro area’s population gained 3,461, for a new total of 2,359,746. The county total increased by 3,718 and is now estimated at 1,227,066.

While modest, these increases mark some of the area’s healthiest population trends in decades and add credence to the notion that slight upticks measured in 2009 and 2010 may be part of a longer-lasting trend.

“The natural population decline in the region is reflecting a change 25 or 30 years ago in the economy. We do expect this moderate uptick to continue into the future,” Briem said.

Positive migration flow at the county level, Briem said, is a much more recent phenomenon and could be attributed to people not wanting to commute as far as they did when gas prices were cheaper five or ten years ago.

However, most migration in the U.S. is for jobs. And while Pittsburgh’s unemployment rate may be high, Briem said, it has still been lower than the nation’s for more than five years.