By Jenny Connelly-Bowen, CBN Graduate Research Assistant

This week, we’re sharing maps that track the spread of vacancy in St. Louis City from 1970 through the present. These were compiled in QGIS using 2011-2015 American Community Survey (ACS) Five-Year Estimates. This data measures vacancy by census tract as a percentage of vacant units out of all housing units. Here’s how ACS defines housing units and vacant units (see pages 7-8 of their most recent Subject Definitions PDF):

  • Housing Unit: A housing unit may be a house, an apartment, a mobile home, a group of rooms or a single room that is occupied (or, if vacant, intended for occupancy) as separate living quarters. Separate living quarters are those in which the occupants live separately from any other individuals in the building and which have direct access from outside the building or through a common hall. For vacant units, the criteria of separateness and direct access are applied to the intended occupants whenever possible. If that information cannot be obtained, the criteria are applied to the previous occupants. 
    • Both occupied and vacant housing units are included in the housing unit inventory.
    • Boats, recreational vehicles (RVs), vans, tents, railroad cars, and the like are included only if they are occupied as someone’s current place of residence.
    • Vacant mobile homes are included provided they are intended for occupancy on the site where they stand. Vacant mobile homes on dealers’ sales lots, at the factory, or in storage yards are excluded from the housing inventory.
    • Also excluded from the housing inventory are quarters being used entirely for nonresidential purposes, such as a store or an office, or quarters used for the storage of business supplies or inventory, machinery, or agricultural products.
  • Vacant Housing Unit: A housing unit is vacant if no one is living in it at the time of interview. Units occupied at the time of interview entirely by persons who are staying two months or less and who have a more permanent residence elsewhere are considered to be temporarily occupied, and are classified as “vacant.”
    • New units not yet occupied are classified as vacant housing units if construction has reached a point where all exterior windows and doors are installed and final usable floors are in place.
    • Vacant units are excluded from the housing inventory if they are open to the elements, that is, the roof, walls, windows, and/or doors no longer protect the interior from the elements.
    • Also excluded are vacant units with a sign that they are condemned or they are to be demolished.

On the maps below, shaded census tracts are tracts where 25 percent or more of that tract’s total housing units are classified as vacant. Listed in the bottom right corner of each map is a total of how many tracts meet this specification each year.

The spread of vacancy across the City of St. Louis in the past 40 years has been striking. In 1970, only two census tracts had 25 percent or more housing units classified as vacant. But according to the latest ACS data available, 44 City census tracts now meet this criteria. The distribution of tracts with high vacancy varies by decade, but remains consistently concentrated in North St. Louis City through the present day.

If you would like more information about how these maps were compiled, please contact us at cbn@umsl.edu. To access maps from previous editions of the Community Builders Exchange, click here.