The drop comes as the population of the city itself has slowly increased in recent years to about 656,000.

The studies did not include data on what exactly is happening to these families, but to Barry Bluestone of Northeastern University the cause is clear.

“Working families are just moving farther and farther away from the central city,” said Bluestone, director of the Dukakis Center for Urban and Regional Policy, which analyzed in-depth census data compiled every 10 years to track the pace and scope of the decline.

Boston Globe