Washington is an important wine-growing region located on the Pacific Northwest Coast of the United States famed for its white Chardonnay and Riesling wines, and the red from Merlot, Cabernet Sauvignon and Syrah as main varieties grown in the region. The first plantings of vines were made at the beginning of the 19th century and expanded vastly in the middle of the 20th. Washington's climate in the west on the Pacific coast is mild and humid, and in the small American Viticultural Area AVA Puget Sound are grown mainly white grape varieties on the other side, behind the Cascade Mountains, which are up to 4,400 metres high, is the major growing area of Columbia Valley. Most of the vineyards in a desert-like area with dry hot summers and arctic cold winters and due to the shortage of rain, artificial irrigation from the waters of the Columbia River, Snake River and Yakima River is required. There are 14 AVAs with the most famous including Columbia Valley, Horse Heaven Hills, Puget Sound, Walla Walla Valley and Yakima Valley.