"This is a population growth and retention strategy," the mayor said. Lowering property taxes and improving the school system are aspects of keeping people who live here satisfied, she said.

With the annual exodus of people from the city dropping by 2,000 in the new estimate, retention seems to be improving. Whether Baltimore's policies and laws have much to do with retention, and the immigrant influx, is debatable.

There is a larger factor— the improving economy — that likely controlled Baltimore's growth last year, said William H. Frey, a demographer with the Brookings Institution in Washington.

"Everywhere shows gains in immigration," Frey said of the new Census Bureau estimates. That's because the economy's looking up, so more immigrants think they will be able to find jobs, he said.

And resident retention has improved for cities because mobility was reduced, he said. People were less willing to commute during the economic downturn, so not as many people were moving to the suburbs, he said.

Mark Goldstein, an economist with the Maryland Planning Department who studies the state's population changes, said the new data show that counties farther from urban centers are losing people while closer-in counties are gaining.

"Growth is much more concentrated," Goldstein said. From the housing boom period of the mid-2000s, when people were moving farther away from cities, the trends have "almost completely reversed," he said.

Garrett and Allegany counties, in Western Maryland, four counties on the Eastern Shore and Carroll County all lost small numbers of people from July 2011 to July 2012, according to the Census Bureau estimates. Anne Arundel, Baltimore and Howard counties, meanwhile, each gained more than 5,000 residents.

Montgomery County, close to Washington, broke the 1 million resident mark. The Census Bureau estimates that it gained 13,000 people during the 12-month period.

Baltimore City Council President Bernard C. "Jack" Young said he's pleased that Baltimore is finally on the positive side of the ledger like the suburban counties. But he's long believed that Baltimore's population count has been low, he said.

"I would say that we gained more than that," Young said. Like Rawlings-Blake, other civic leaders and some demographers in the region, Young thinks the 2010 Census count, on which the Census Bureau's annual population estimates are based, was too low.

"People really did not fill out that census," Young said.

Baltimore officially challenged the 2010 Census count last year, submitting a record of nearly 16,000 households the city believes were missed in the tally. That could mean 30,000 people, give or take, were not counted and that the city didn't lose population from 2000 to 2010.

The city's challenge is still pending, said Tom Stosur, the city's planning director.

Last year, the state's Planning Department released projections of how long it will take Baltimore to regain the 30,000 people that the Census Bureau says the city lost between 2000 and 2010.

It won't be until 2040, the planning department estimates, that the city's population will be back above 650,000, where it was 13 years ago.