The city is moving toward grouping portions of its biggest colleges and universities in far-flung underdeveloped neighborhoods such as Long Island City, Governors Island, the South Bronx, and downtown Brooklyn.

With the city’s 113 colleges and universities together projecting a need for 20 million square feet of real estate over the next few years for new dormitories, laboratories, and classrooms, they would likely have to expand into places such as Westchester or New Jersey if they don’t pool their resources and share space, city officials said.

Sharing academic buildings and residence halls could create the unusual scenario of a Columbia University professor living next to a City University of New York dean, and their students passing each other in the hallways of a building in Queens.

In an effort to brand New York as the country’s biggest, fastest-growing college town, the Bloomberg administration has created a higher education task force charged with developing these “university centers.” While 23 of New York’s largest universities so far have said they would consider developing communal real estate with the city’s help, some in the academic community say they worry it could detract from the unique identities of their individual institutions.

“On paper, it might sound nice to facilitate an intellectual community, but I don’t know in practice if it would happen,” an assistant professor of French at New York University, John Moran, said.

Some students said communal learning and living could weaken the bonds they establish with their colleges.

School administrators have been hesitant to sharing laboratories and classrooms in remote neighborhoods, city officials said, in part because of the difficulties of coordinating their class schedules.

“The shared student or faculty housing is a much easier lift,” the vice president for business development at the city’s Economic Development Corporation, Teresa Vazquez said. With the city’s crowded real estate market, the city is pushing colleges and universities to think outside the box about their expansion plans.

“Twenty million square feet is not something easy to come by,” Ms. Vazquez said. “We still need to make schools more aware of the development potential of places like Long Island City to prevent schools from going outside of New York City to expand.”

Ideally, schools such as Columbia, New York University, Barnard, CUNY, the New School, Pace, Fordham, and Cooper Union — all of which have expressed interest in sharing buildings — would create intellectual communities in some of the city’s struggling neighborhoods.

“There is no major academic investment there,” Ms. Vazquez said of Long Island City, where the city has invested $40 million in infrastructure to make the neighborhood more attractive to private investors. “It’s new territory for them.”

Ensuring that such institutions grow within the city would also give a boost to economic activity in struggling neighborhoods, and would keep in New York all of the 84,000 jobs that higher education creates, Ms. Vazquez said.

The city is aiming to have its communal expansion plans nailed down by next fall.

“Our current explorations with the EDC are focused on housing, but it could also provide promise for academic programs that have synergy with the developing economic milieu of the area,” the assistant vice president for campus planning and design at NYU, Lori Mazor, said in an e-mail message.

The city’s shared resources proposal is based on a similar plan in Chicago, where the city granted land to DePaul University, Roosevelt University, and Columbia College to construct a shared dormitory for their students.

So far, the city is only offering its help, but neighborhood groups say they would encourage the city to offer up land or financial incentives to institutions that agreed to share space in developing neighborhoods. “If the city had land that it made sense for this kind of use, that should be on the table,” the executive director of the Greenwich Village Society for Historic Preservation, Andrew Berman, said. “We’ve been urging NYU for years to work with the city to find space outside of our neighborhood which is becoming oversaturated every day.”