The ability to acquire and convey vacant real estate to developers, when managed efficiently, can give older cities such as Philadelphia a competitive advantage over built-out suburban areas. However, in Philadelphia and many other older cities, most of the vacant properties are small, with many less than half an acre in size. Few postindustrial cities resemble Detroit and St. Louis, where large parcels of cleared land can be found, in some cases extending over several blocks. In addition, cities like Philadelphia have many largely vacant blocks that contain single or clustered occupied houses; assembling such blocks for development will necessitate decision-making about relocation and replacement housing for displaced residents.