"You're getting the extremes--the young and the not-so-young," Retsinas says. "That kind of population sees city government differently than a population of families with young children."

Extremes are becomingly increasingly evident in wealth as well as age--an effect that Retsinas calls the "hourglass economy."

As in the U.S., the stable middle class in Cambridge is disappearing and being replaced by the affluent and the very poor.

"The changing demographic changes the way people perceive city government," Retsinas says.

"For some at the high end, city government becomes less relevant. For some at the lower end, they're so busy surviving that when they need city government, it's most likely because of a crisis," he says.

State Rep. Alice Wolf says she has noted an upswing of people in extreme need. She says her office has been deluged by people who can't pay their bills.

"On a continual basis, we have people who are calling who are homeless, who are about to be evicted, who can't pay their rents," Wolf says.

On the other side, the well-off have been choosing more and more to send their children to private schools--removing an important link with the rest of Cambridge's famously diverse community.