def add_zctas(urban_areas)
      foreach(data_file(USGeoData::ZCTA_URBAN_AREA_REL_FILE), col_sep: "|") do |row|
        urban_area_geoid = row["GEOID_UA_20"]
        zcta5 = row["GEOID_ZCTA5_20"]
        overlap_land_area = row["AREALAND_PART"].to_f * SQUARE_METERS_TO_MILES