There are only 20 conservation districts in Dallas, all but three of which are clustered in Oak Cliff and East Dallas. Two are in Oak Lawn and one is in North Dallas. Those are the neighborhoods where homeowners agreed to be hogtied by the city; setbacks, structural heights, design, and density can all be codified. There are also 21 historical districts, which are even more strict, aiming to preserve original structures exactly as they were first built. Most neighborhoods don’t have that protection. And, to be fair, most neighborhoods don’t have the collection of Craftsman and Tudor homes of Hollywood/Santa Monica. Most of the conservation districts protect homes built in the early 1900s through the 1940s. Neighborhoods with homes built in the 1950s and 1960s are largely left alone. A fast way to tell if a block faces the teardown trend in the next few years is to type a few addresses into the Dallas Central Appraisal District’s website. Is the land hovering around $275,000 and the house itself worth just a fraction of that? Bingo. Those numbers point toward a bulldozer. And, frankly, the houses can be in pretty poor shape. Since 2012, there have been 6,530 demolition permits issued by the city of Dallas for single-family homes or duplexes, according to data provided by the Building Inspection Department and published here for the first time. More than half of those, 3,562, are located in council districts 2, 6, 11, and 13, an area that includes downtown and shoots north like a hook that hangs over the Park Cities.