The developer of East Market, a mixed-use project between 11th and 12th Streets along Market Street, may add 250 more residential units at the site in response to what it sees as strong demand for living spaces in the area.

National Real Estate Development managing director Daniel Killinger said during an appearance at the Urban Land Institute conference in Philadelphia Thursday that his company will decide next month whether to pursue the expansion.

The new units would add about 20 stories to what has been intended as a two-story retail building at the corner of 12th and Market Streets, Killinger said. The company already plans a 322-unit residential tower as part of the project.

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