Harvard demographic studies are showing signs of how the housing market’s crash could end. The growing population will fuel demand for housing, the study by the Joint Center for Housing Studies of Harvard University found. Single-person households are the fastest growing market, as more people get married later and divorce more. Meanwhile, new developments have been sharply reduced, restricting supply. The Northeast could see signs of the turnaround as early as spring 2009. Between 2010 and 2020, the number of U.S. households will grow by more than 1.4 million a year, the study showed.