One of the main reasons why there are little options for sprawl-like development today is zoning. Or more specifically, the way we zone.

A simple description of zoning is the practice of isolating land-uses into zones of their own. Residential areas, commercial areas, industrial areas, recreational areas and so forth. Cities will typically have their own zoning policies as well. These are instructions that regulate e.g. the types of housing allowed in a residential zone.