Board of supervisors

A board of supervisors is a governing body that oversees the operation of county government in all U.S. counties in Arizona, California, Iowa, Mississippi, Virginia, and Wisconsin as well as 16 counties in New York. There are equivalent agencies in other states.

Similar to a city council, a board of supervisors has legislative, executive, and quasi-judicial powers. The important difference is that a county is an administrative division of a state, whereas a city is a municipal corporation; thus, counties implement and, as necessary, refine the local application of state law and public policy, while cities produce and implement their own local laws and public policy (subject to the overriding authority of state law).

Boards may pass and repeal laws, generally called ordinances. Depending on the state, and the subject matter of the law, these laws may apply to the entire county or to only unincorporated areas not within the jurisdiction of a city. The board is also responsible for approving the county budget. County governments may collect state taxes and, in some states, they may also levy taxes, such as property or sales tax.

In some states, including Michigan, and in some New York counties until recently, county governing boards were composed of township (Michigan) or town (New York) "supervisors". These are the chief elected officials of each civil township. Boards of Supervisors were originally composed of the various town/township supervisors from across the county. This system gave every township one vote on the county board regardless of its population, resulting in less populous townships having influence in decision-making that was disproportionate to their populations.

Both Michigan and New York changed how they elected county boards by dividing counties into single member districts, drawn so that each district has more or less the same sized population or with each township's vote weighted by population, under order from the Warren Court (see Reynolds v. Sims). In Michigan, the new board model was implemented in 1968. The name "Board of Supervisors" was changed to "Board of Commissioners" in 1970, however, to avoid confusion with township government (where the term "Supervisor" was still used). In New York, the new boards were called "county legislatures" (and their members, "county legislators"), but not every county has adopted this system. Those that retained the old boards of supervisors after the 1960s assigned each member a proportional vote based on the population represented.

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