A Sonoma & Napa Geography Lesson

What does someone mean when they say "Sonoma" or "Napa?" It's not always clear. A geography lesson follows.

Counties
Both Sonoma and Napa are counties sharing a border.

Towns
There are towns of Sonoma and Napa in their respective counties.

Valleys
Both are AVAs, or officially recognized grape-growing areas. Napa Valley is world famous, of course, and is what most people mean when they say Napa. Napa Valley actually covers just about the entire county of Napa, though most think of it as just the valley floor (there are mountains on three sides). Sonoma Valley is one of many AVAs in Sonoma County.

Interpretation
When someone says "Sonoma" it can mean the town or county depending on context. That's why it's always good to use county or valley when you aren't talking about the town. When someone says "Napa" it can mean the valley floor or the town, again, depending on context. When a visitor says "Napa" I assume they are talking about the valley. But it's always good to say county, town of, or valley so others know what you mean.

Sonoma Valley runs from about the town of Sonoma to Santa Rosa
Napa Valley from the town of Napa up past Calistoga and
into the hills on the east and west.