4. Buffalo, NY
Population Change 2000-2009: -21,970
Population Percent Change 2000-2009: -7.52%
Home Vacancy: 17.2%
The collapse of the canal and improvements in the energy industry which made Niagara Falls less important led to the mass migration from the city which continues to this day. In the 1970′s alone, Buffalo lost more than 100,000 residents, roughly a third of its current population.