In 1981, Napa Valley became California’s first federally-recognized American Viticultural Area (AVA). About an hour by car from San Francisco, it is compact (5 miles across at its widest point), representing only about 4% of wine production in the Sunshine State, which has not dampened its prowess as a wine region. Impressive facts include its fairly pure Mediterranean climate and its almost-incredible diversity of soil types(12 distinct soil orders), combined with varied topography, including protective mountains, which can produce different microclimates.Napa Valley has 16 other AVAs nested within it, each with distinct characteristics.

If you see “Napa Valley” on a wine label, it means 85% of the grapes used to make the wine came from within the valley, but not necessarily from one of the sub-regions. Cabernet Sauvignon, Chardonnay, Pinot Noir, and Merlot are the four most-planed grape varieties in Napa Valley.

A Prussian immigrant, Charles Krug, established Napa’s first winery in 1861 on an impressive 540 acres of land his wife—Carolina Bale—inherited. Krug had studied winemaking with Hungarian immigrant Agoston Haraszthy, among others, starting in the 1850s. Haraszthey, among other accomplishments, introduced more than three hundred European grape varieties to California. Indeed, in the 19thcentury, vine planting were often a patchwork of different varietals and wines were often “field blends.” Nonetheless, Krug was, if not prescient, then lucky and knowledgeable, having started the growthtoward what is today America’s wine capital.

Today, great precision is applied to Napa wine creation. “We have an intimate understanding of the connection between terroir and vine,” says the Napa Valley Vintners association,“and have realized just how the diversity of Napa Valley’s soil, climate and terrain allow us to grow distinctive wines from specific areas within the valley.” The other AVAs in the valley include: Atlas Peak, Calistoga, Chiles Valley, Coombsville, Diamond Mountain District, Howell Mountain, Los Carneros, Mt. Veeder, Oak Knoll District of Napa Valley, Oakville, Rutherford, St. Helena, Spring Mountain District, Stags Leap District, Yountville and Wild Horse Valley.

The valley is createdby the VacaMountains to the east and the Mayacamas to the west and north, with Sonoma County on the other side.Internal hills create smaller valleys. The Rutherford Bench lies in the center of the valley floor. Southern-end soils aremainly made up of ancient oceanic sediments whileat the northern end of the valley the soil featuresa large volume of volcanic lava and ash. Small hills that emerge from the middle of the valley floor near Yountville revealthe Napa Valley’s ancientvolcanoes.The valley is about 30 miles long. The valley’s southern end opens to San Pablo Bay, and is cooler; the northern end is more sheltered,andwarmer.The mountains and hills block rainy weatheron the eastern side, a phenomenon known as a “rain shadow” where onone side of the mountains, wet weather systems drop rain,while on the other sidesuchprecipitation is blocked; thusthis area is much drier than the rest of the valley.

In the United States, by federal law, political boundaries like counties, states, or even the entire country can be used to indicate where the wine was made and where at least 75% of the grapes used to make the wine originated. Thus, you could have a wine labelled “United States wine,” though this is not very common.

California is by far the largest wine-producing state in the US, making more than86% of US wine. It has numerous American Viticultural Areas (AVAs) within its boundaries. AVA regulations do not dictate crop yields, methods of production, vineyard planting densities, etc. as in the Old World, but they do give a geographic definition to awine’s place of production.For an AVA-labelled wine, at least 85% of the grapes used to make the wine have to come from within that AVA. But not so for political boundaries, which require 75%.

So, if the wine is labelled as just “California” with no reference to another AVA, then by federal law at least 75% of the grapes must have come from California and wine was produced there. The same would be true for, say, Oregon, New York, or Washington states. There’s a caveat, however. California law requires 100% of the grapes to come from within the statefor any wine labeled with the appellation of origin “California”or anyof its geographical subdivision, whichis obvious stricter than the federal standard.

This is a pretty common appellation, as many California winemakers source grapes from throughout the state. There may be additional information from the winery about where the grapes were sourced, even for a “California wine,” and although in general better wines come from smaller areas or specific AVAs, this does not necessarily mean a wine with a state-level appellation is inferior. It may just be that the winemaker wanted to create a blend using grapes from different producers throughout the state to achieve a specific objective in terms of style, flavor, etc.

Alexander Valley is an American Viticulture Area (AVA) within Sonoma County, California. If a wine is labelled Alexander Valley, then 85% of the grapes used to make the wine musthave from there. The Valley has a long history of grape growing and winemaking stretching back to the latter half of the 19thcentury, with a new wave of modern winemaking commencing in the 1970s. This AVA is north of Healdsburg in Sonoma Countyand home to the city of Cloverdale. TheRussian River bisectsthe valleywith vineyards on both sides.You can drive through it on Hwy. 101. Within the famed Sonoma wine producing regions, Alexander Valley is the largest AVA and also is more completely planted withVitis viniferathan any other in the county.

Longstanding and pioneering producers include Simi, Rodney Strong, and Chateau Souverain, who recognized the potential of its terroir,with an overall Mediterranean climate, cool wet winters, hot dry summer, but always with vital cooling coming from Pacific Ocean access.It averages over 1800 degree days receiving about 32 inches of rain each year. The Alexander Valley is famed for its Cabernet Sauvignon wines, but produces other varietals as well, particularly other Bordeaux varieties. Cabernet is King, grown best on the western slopes of the Mayacama Mountains. Vineyard elevations range from 400 to 2500 feetabove sea level. Fog often develops in the valley at night. The fog disappears sooner for higher elevationvineyards, but poorer soilson the slopes extends grapematuration a week to two weeks longer than the benchlands and valley floor. 80% of the Alexander Valley vineyards are on thebenchlands, withthe majority in the middle of the valley at the base of the Mayacama also planted to Cabernet Sauvignon. Resulting winequality stemsfrom the depth and compositionof these soils.