The most famous American wine region, and one of the most highly regarded in the world. The first grapes were planted here, northeast of San Francisco (with a climate influenced by an arm of San Francisco Bay), in the mid-19th century; one of the earliest commercial wineries, Charles Krug, still in operation, was founded in 1861. Wineries proliferated in the late 19th century and, after a downturn during Prohibition, the Napa wine scene continued to expand. The so-called "Paris tasting" (later renamed "The Judgment of Paris") in 1976 — in which a panel of French wine experts rated cabernet sauvignon and chardonnay from the Napa Valley higher than their famous and far more expensive French counterparts — brought international renown (and higher prices) to the valley's wines. While these remain the two most widely grown grapes in Napa (the cabernet is particularly highly regarded), scores of other varieties are planted and do well here. There are now at least 450 wineries in the Napa Valley (700 or so in Napa County as a whole), from modest warehouse facilities to multi-million-dollar showplaces mimicking European castles, and the area has become a major tourist attraction.
Sonoma winemakers like to think of their region as a quieter, less glitzy alternative to the Napa Valley — though in fact it produces roughly 50 percent more grapes annually, covers more than twice the ground, and boasts about three times the population. Sonoma had grapes earlier than Napa did, too, with the first plantings in 1812. A Hungarian writer and entrepreneur named Agoston Haraszthy, called "the father of California viticulture," bought a property in Sonoma and in 1857 founded the still-extant Buena Vista winery there (it is the oldest commercial winery in the state). He later traveled around Europe collecting vine cuttings and is said to have introduced some 300 new varieties to California (among them, according to legend, zinfandel — though this has been disputed). There are various soil types and microclimates in the county, and many grape types have thrived, with chardonnay and pinot noir being perhaps the most famous, though Sonoma's Dry Creek Valley is notable for its zinfandel, and there is excellent cabernet sauvignon and merlot made throughout the region.
More correctly called Los Carneros, this region in the foothills of the Mayacamas Mountains spans parts of both Napa and Sonoma counties. Cooler than most other parts of the region, it produces wines with good acidity, typically lighter and more elegant than their lowland counterparts. Pinot noir and chardonnay are the specialties here.
A region of Sonoma County with a comparatively cool climate, the Russian River Valley — named after the Russian-America Company, whose traders explored the valley in the early 1800s — is famous above all for its chardonnay, with pinot noir a close second (about 20 percent of California's pinot noir plantings are here). E. & J. Gallo and Kendall-Jackson are major presences in the area, though there are many small producers as well.