The 10 US cities where it's hardest to build affordable housing

• Restrictive zoning, often originally designed to exclude people of color, persists in metros across the US. 
• A new database created by the Eviction Lab at Princeton University ranks metro areas. 
• The top 10 most exclusionary metro areas include coastal hubs as well as a few Midwestern cities.

The nation's capitol and its surrounding suburbs have the most restrictive and exclusionary zoning of any metropolitan area in the US, according to a new "Zoning Restrictiveness Index" and database created by The Eviction Lab at Princeton University.