Phoenix and Las Vegas are cities that have specialized in the type of low-density, auto-dependent development that many progressive planners deride as wasteful and old-fashioned. And the proposed creation of Interstate 11, which could very well end up being the last mega-project of the superhighway era, confirms how car-centric this stretch of the Sun Belt remains. In some sense, the potentially monumental undertaking could fulfill a psychological need, a sort of obsessive-compulsive desire to “complete” the national highway grid. Cartographically, it would confer a new status on the route, which would no longer be considered a secondary backwater road. Economically and demographically, supporters say the highway would lead to a new era of growth in an already fast-growing part of the country and create a job-generating megalopolis that would allow the Southwest to compete with regional powers across the globe. Others, meanwhile, argue that the new ribbon of highway would collapse any hope of sustainability in a part of the country where natural resources are strained and any growth comes with a sure environmental cost. California-based writer Josh Stephens jumps into the discussion, crunching the numbers and asking whether a region essentially birthed by highway culture should continue its love affair with asphalt.