America's favorite red wine passion, Merlot is known for its role, sometimes as the primary varietal, in the great wines of Bordeaux. It is, by nature, an earlier maturing grape than Cabernet Sauvignon, and tends to have rounder, plummier, more forward fruit with lower tannins so it is often used to soften and round out the edges of the more astringent Cabernet. It is the grape of choice in Pomerol and St. Emilion, and represents the basis for some of America's most popular red wines, particularly from Washington, Napa Valley, Sonoma Country, the Central Coast, Long Island, Texas, and yes, Colorado.
This is the largest region in terms of acres, and represents over half of Washington's vinifera varieties. Most vineyards across the state source their grapes from this area.