A mile east of the School Book Depository in downtown Dallas lies a section of the city called Deep Ellum, a mottled array of old brick structures, where wild graffiti and gaudy murals decorate the walls of trendy shops, loft apartments, restaurants, nightclubs, an galleries, and tattoo studios. The area is also home to more conventional endeavors, including a century-old meat market, auto repair shops and a sheet-metal business owned by a Holocaust...