Source: US. Bureau of the Census
Release: Housing Vacancies and Homeownership
This group consists of year-round vacant units which have been rented or sold but the new renters or owners have not moved in as of the day of interview.
US. Bureau of the Census, Housing Inventory Estimate: Vacant Housing Units Rented or Sold, Not Yet Occupied for the United States [ERNTSLDUSQ176N], retrieved from FRED, Federal Reserve Bank of St. Louis; https://fred.stlouisfed.org/series/ERNTSLDUSQ176N, July 30, 2016.