United States

The UC Davis Library dates vineyard planting in what is now California to the Franciscan missions, beginning with Mission San Diego de Alcalá in 1769; the grape they spread became known as the Mission grape. The 18th Amendment, ratified in 1919, banned the sale of alcohol from 1920. The library counts more than 2,500 commercial wineries in the country before 1920 and fewer than 100 that came through Prohibition, which ended in 1933.

The federal appellation rules in 27 CFR 4.25 date from T.D. ATF-53, published on 23 August 1978. The first AVA, Augusta in Missouri, was established on 20 June 1980, and Napa Valley followed on 28 January 1981. On 24 May 1976 a blind tasting in Paris ranked a 1973 Napa Valley Chardonnay and a 1973 Napa Valley Cabernet Sauvignon first against French wines; Time magazine reported the result.

TTB defines an AVA as a delimited grape-growing region whose distinguishing features, such as climate, geology, soils, physical features and elevation, set it apart from surrounding areas. The register separates AVAs within one state from multi-state AVAs; several in the Columbia and Snake River basins cross state lines, and California has the largest number.

The settings differ widely. California's coastal valleys are cooled by ocean air and fog. East of the Cascades, Washington's Columbia Valley is an arid basin on basalt, with soils left by the Ice Age Missoula Floods, and is irrigated. Oregon's Willamette Valley lies between the Coast Range and the Cascades. In New York the Finger Lakes are glacial lakes that moderate temperatures, and the Texas High Plains lie at about 910–1,220 m. These regions are described in their own entries.

TTB states that AVA designations let vintners and consumers attribute a given quality, reputation or other characteristic of a wine to its geographic origin. It also states that establishing an AVA is neither an approval nor an endorsement of the wine produced there. Each AVA petition must show how climate, soils, elevation and physical features differ from the land around it, and the final rules summarise that evidence. The rules therefore describe growing conditions, such as fog in the Russian River Valley or the lake effect at Seneca Lake, rather than a prescribed wine style. The part 9 sections set names and boundaries, not grape varieties or yields.

Under 27 CFR 4.25 an American appellation of origin is the United States, a state, two or three contiguous states, a county, two or three counties in one state, or a viticultural area. A state or county appellation needs at least 75% of the wine from fruit grown there; a multistate or multicounty name needs all of it, with the share of each shown on the label. An AVA needs at least 85% of the wine from grapes grown inside its boundary, and the wine must be finished in the state, or one of the states, where the AVA lies. Under 27 CFR 4.23 a single grape variety on the label needs at least 75% of the wine from that variety.

States may set stricter rules. California requires 100% California fruit for a California appellation, and Oregon requires 95% for its own AVAs and 90% for most varietal names.