Boston Mayor Martin Walsh says the city needs to build 53,000 units of housing over the next two decades to accommodate a growing population and prevent low- and middle-income residents from being squeezed out of the market.

Part of the mayor's plan calls on the city's colleges and universities to build more dormitories, to free up off-campus apartments and save students from living in substandard rental units.

Walsh is calling on $21 billion in private and public construction to boost the city's housing stock by 20 percent and make room for a population expected to jump to more than 700,000 by 2030.

Support for GBH is provided by:

Part of the plan calls for loosening zoning restrictions and providing incentives for building taller buildings. The plan also calls for encouraging development around public transportation hubs.