Two sitting Boston city councillors may be forced to move from their current homes or give up their seats due to Boston population shifts that could transform the boundaries of their current districts. That's one possibility that was raised at a redistricting hearing held Thursday in downtown Boston.

While the city gained residents overall, rising by five percent to 617,594 residents, some parts of the city lost population by official counts, including parts of Dorchester, Mattapan, Hyde Park and Roslindale, and West Roxbury.

The City Council committee tapped to redraw the boundaries of the 9 City Council districts could be forced to move some of the district boundaries northward. And that means two city councillors who live close to the southern edge of their present seats -- District 7’s Tito Jackson and District 8’s Michael Ross -- could find themselves living outside the districts they currently represent.

Ross notes that there will be many scenarios and many maps available to the committee, which is chaired by District 2 Councillor Bill Linehan. And when redrawing districts, the committee can factor incumbency into the decision-making process.

The redistricting committee is expected to hash out a redrawn district map by the end of the year. Any new map would need the approval of the 13-member City Council, the mayor and the secretary of state. City Hall insiders are skeptical a map adversely impacting incumbents would be approved.

Any changes would affect the 2013 municipal election, giving the councillors time to move into a redrawn district in the event that they are left outside newly drawn lines.

The boundaries must be redrawn every ten years, following the US Census.

Jackson lives in Grove Hall and purchased the Schuyler St. house he grew up in. He won the District 7 seat in a special election and is facing three opponents in this September‘s preliminary. Jackson also ran for one of the City Council’s four at-large seats in 2009.

District 7 largely covers Roxbury and Dorchester, but also includes precincts in the South End and Fenway.

Ross, elected to the council in 1999, moved to Mission Hill four years ago after living on Beacon Hill. District 8 includes Back Bay and Beacon Hill, Fenway and Kenmore, Mission Hill, a precinct in the West End and a pair of precincts in Allston.

Ross, who lives on Parker Hill Ave., is running unopposed this year.

Linehan compared the redistricting process to a “Rubik’s cube,” a challenge made difficult by inequity in the size of precincts: Some voting precincts are larger than others because the city has not redrawn those in over 80 years, and doesn’t plan on tackling redrawing precincts in time for this round of redistricting. Precincts are considered building blocks for redistricting at the local and statewide level.

Each council district must have between 72,052 people and 65,190 people, according to a City Council analysis based on new US Census figures. District 3’s Dorchester must pick up 7,700 people, while Mattapan must pick up 6,400 people. Hyde Park, West Roxbury, and Roslindale must also pick up residents.

Linehan’s committee is holding four hearings on redistricting: Sept. 20 at the George Wright Golf Course on West St.; Oct. 13 at the Franklin Park Golf Course on Circuit Dr.; Oct. 18 at the Reggie Lewis Center on Tremont St.; and at the New England Carpenter’s Hall on Dorchester Ave. on a date to be determined. All the hearings start at 6 p.m.

The first hearing was already held on Thursday night at Suffolk University Law School. But attendance was limited to a pair of reporters, Councillors Linehan and Maureen Feeney, and several City Hall staffers.

The attendance level prompted Linehan to quip, “I’ll draw the map on the way home.”