The rental vacancy rate is the proportion of the rental inventory that is vacant for rent.
Source: US. Bureau of the Census
Release: Housing Vacancies and Homeownership
US. Bureau of the Census, Rental Vacancy Rate in the Northeast Census Region [RRVRNEQ156N], retrieved from FRED, Federal Reserve Bank of St. Louis https://research.stlouisfed.org/fred2/series/RRVRNEQ156N/, September 2, 2015.