What is an AVA or Appellation
An American Viticultural Area (AVA) is a delimited grape-growing region distinguishable by geographic features, with boundaries defined by the United States government's Alcohol and Tobacco Tax and Trade Bureau (TTB). The TTB defines these areas at the request of wineries and other petitioners. There are 173 AVAs in 30 states, with 97 of them in California. They range in size from the Ohio River Valley AVA at 26,000 square miles (67,300 km²) across four states, to the Cole Ranch AVA in Mendocino County, California, at only 62 acres (25 hectares).
Unlike most European appellations, an AVA specifies only a location. It does not limit the type of grapes grown, the method of vinification, or the yield, for example. Some of those factors may, however, be used by the petitioner when defining an AVA's boundaries.