Zoning is a purely a county, city, or municipal affair. Though zoning laws are somewhat universal, the classifications used to describe zoning are not uniform from place to place. For instance, it is not uncommon to find that zoning laws that apply to one part of the community are different in another part of the town, or that one town does a mix of residential uses with some commercial uses but a neighboring community might outlaw such mix.
Typically, zoning laws are made on a local level because the purpose of the rules is to create a community that makes sense for the residents who live there. A local city, town or state has a greater and broader interest in creating areas that are comfortable for people, and has a better idea of how to do so in a way that makes sense for the local citizens than a more distant governing body.
In addition, while local governments and zoning boards are generally in control of zoning, the people in a community themselves have some control over zoning as well. For example, if an individual wants to do something that his or her home is not zoned for, such as running a home business in a residential zone, in most cases he is able to get an exception to the zoning laws as long as the local board and his neighbor's agree. For example, he may have to get all of his neighbors to sign something permitting the exception and allowing him to open the business, or he may have the local zoning board vote on his request.
To better understand this and other zoning laws, it is a good idea to contact your local zoning board. Depending on where you live, you may be able to attend a meeting and watch first hand how decisions are made.