Although federal influence is undeniable, I'd argue that zoning remains mostly a local function, with regulations crafted and enforced at the municipal, county and sometimes regional level. Since New York City passed our country's first zoning regulations almost 90 years ago, partly to repel the penetration of industrial concerns into other districts of the city, just about every town and city in the United States has established its own set of zoning regulations.

While the intent of these regulations can often be traced back to legitimate public health concerns (we don't want the leather tannery to locate next door to the apartment building) zoning has been taken to the extreme so that professional offices, neighborhood markets and sidewalk cafes can be cast as dangers to the "residential character" of neighborhoods. "High density" and "mixed-use" remain very dirty words (at least in my state), despite the fact that they can also be used to describe some of the most desirable residential neighborhoods in our country.