KATE CLARK and her husband had their first child, son August, last June and plan to continue living in the city.

"We're here. We're not going to the suburbs," she said.

Philadelphia is affordable, walkable, and has a great art scene and "tons of young parents," said Clark, who lives in the East Passyunk section of South Philly. And you "have a chance to make an impact on your city."

Her son is one of the new residents who have contributed to an estimated growth in the city's white population since the 2010 census, reversing a 60-year decline of whites in the city.

According to new estimates being released Thursday, Philadelphia saw a slight jump in the number of whites living here from April 1, 2010, to July 1, 2011. The estimates show the city gained 3,980 whites, or a 0.7 percent increase, for a total of 569,215 whites in July. Whites make up 37 percent of the city's total population, as they did in 2010.

Clark, a planner at the Philadelphia Corporation for Aging, and her husband, David Clayton, a curator at the Breadboard gallery at the University City Science Center, are members of the East Passyunk Crossing Civic Association. Clark co-founded the association's education committee, which will be working to support the neighborhood Southwark School with volunteer recruitment. She plans to send August to the school.

Clark and Clayton moved to the city from grad school at Syracuse University in 2008, first renting in Fairmount before buying their house near 10th and Morris streets in 2010.

Experts say it's not possible from the new data to determine whether the estimated increase in the city's white population came from births or from new people moving into the city. They also cautioned not to look too much into yearly estimates. "We're never sure of how good any year-to-year estimate is until the 10 years have gone by between 2010 and 2020," when the census counts will be taken, said David Bartelt, emeritus professor of geography and urban studies at Temple University.

Paul Levy, president and chief executive of the Center City District, has noted that young parents have chosen to stay in the city after having children, particularly in the Center City area, and has said that office jobs in Center City and the health-care and education jobs in University City have helped to keep young adults here.

Michelle Schmitt, project coordinator at Temple's Metropolitan Philadelphia Indicators Project, noted that the Center City and West Philly neighborhoods saw increases in their white populations from 1990 to 2010.

At the height of Philadelphia's population, in 1950, the city had a population of 2.1 million people, 1,692,637 of whom were labeled as white. Whites then most likely included people of Hispanic and other origin. In that census, people were labeled "white" or "nonwhite." It wasn't until 1980 that the census included a non-Hispanic white category.

William Frey, a demographer at the Washington-based Brookings Institution, said that Philadelphia's decline in white population in 1950 followed a similar trend seen among big metropolitan areas and cities. During the 1950s and '60s, and especially in the '70s, there was white flight to the suburbs for jobs, bigger houses and safer schools, he said.

Although the white migration to the suburbs has recently slowed down, a large proportion of whites still live in the suburbs, he said. Whites have returned to some select cities, he said.

Janice Madden, a sociology professor at the University of Pennsylvania, noted that "African-Americans have been suburbanizing at a faster rate than whites since 1990 in large cities throughout" the U.S.

In the latest estimates, from last July, the city's black population continued to show a slight decrease of 0.4 percent, similar to its decline from 2000 to 2010. The number of Hispanics and Asians, meanwhile, was estimated to have increased by 3 percent and 2 percent, respectively, from 2010 to 2011. n

Contact Julie Shaw at 215-854-2592 or shawj@phillynews.com.