The city is expected to add one million more residents by 2040, but there likely won't be room for hundreds of thousands of them unless a small city of new housing is built, according to a report by a Columbia University think tank.

The report said the city would reasonably reach a population of more than 9 million in less than 30 years, with the authors predicting that New York will remain a magnet for immigrants, artists and young professionals seeking their fortune. The growth is slightly slower than that predicted by the Bloomberg administration, which has said there will be a million more New Yorkers by 2030, according to the Wall Street Journal.