One of the cornerstones of urban planning in many cities, zoning codes are sets of regulations used by local governments to control land use by defining what can and cannot be built in specific neighborhoods, what buildings can look like, and what uses can coexist in the same areas. Use-based zoning is an important tool for guiding development in most U.S. cities, but more recently, cities are turning to form-based codes, which focus on design rather than use. Local jurisdictions often push back when states attempt to preempt local control of zoning through statewide regulations that mandate higher density.