It is remarkable that an industry essentially less than a half-century old could capture the attention of the American wine-buying public to the degree that California has. Powerful consumer interest in California wine is driven by two major factors. The more obvious reason is that California's best wines, which come from grapes grown in a benign climate featuring endless sunshine, very warm summer days, and generally dry harvests, and wonderfully fruity, full, and satisfying, and rarely too austere or tannic to be enjoyed from day one.
California is blessed with an extraordinary range of soils and microclimates, allowing for the successful cultivation of many varieties. In at least three out of four years, the best sites produce healthy, ripe fruits that are the envy of European producers in more marginal climates. The other reason Americans buy so much California wine is that California is the home team. Clearly, a high percentage of domestic wine drinkers are more comfortable buying American wines (and not just wines of California) than imports. Then, too, foreign bottles are generally identified by place name, rather than by the more familiar varieties that American wine drinkers have come to know and enjoy.
Moreover, in much of North America, outside the top 15 or 20 largest metropolitan markets, consumers have limited access to imported wines even if they wanted to buy them.
For many, Napa Valley is California wine, and Cabernet is king in Napa Valley. Meanwhile, the Burgundy varieties Chardonnay and Pinot Noir have gravitated to cooler areas, generally closer to the Pacific, such as the western stretches of Sonoma County, the Anderson Valley in Mendocino County, and the Santa Maria and Santa Ynez valleys within Santa Barbara County. Syrah vines have yielded interesting wines in a range of styles all over the state, in regions as disparate as Mendocino County, the Sonoma coast, Carneros, Paso Robles, and Santa Maria Valley. Very good Zinfandel similarly comes from multiple growing areas, although to date the age-of-vines variable has been almost as important as geography. Zinfandel, though its roots are in Europe, is a true California original and the only California wine imitated abroad. It's also a variety of which there are still significant plantings of very old vines, in some cases dating back to the end of the 19th century.