subappellations

Subappellations, commonly referred to as sub-AVAs, are formally defined subdivisions of a larger wine appellation. They denote smaller geographic zones that share distinctive environmental characteristics—such as specific climate, soils, and topography—that influence grape growing and wine style. The recognition of subappellations acknowledges within-region diversity and allows producers to communicate a more precise origin.

In practice, sub-AVAs serve labeling and marketing purposes, helping consumers understand terroir-driven differences and enabling winemakers to highlight a more specific origin while still referencing the broader appellation.

Regulatory framework: In the United States, the concept operates under the American Viticultural Areas system. The Alcohol and Tobacco Tax and Trade Bureau (TTB) regulates AVA and sub-AVA designations on labels. Wines labeled with a sub-AVA name generally must derive the majority of their grapes from that sub-AVA, while also often including the parent AVA on the label.

Internationally, similar ideas exist under different regulatory regimes; the precise term subappellations is mainly used in American viticulture literature.

Examples: Within Napa Valley AVA, several widely recognized sub-AVAs include Stags Leap District, Rutherford, and Oakville District. Other Napa sub-AVAs include Howell Mountain. Numerous other AVAs in the United States use sub-appellations to express local terroir.