Since it began in the 1820s, wine-production in Washington state has gone from strength to strength, with many of the finest United States wines coming out over the past twenty years hailing from this region. Today, the state is the second largest US producer of wines, behind California, with over forty thousand acres under vine. The state itself is split into two distinct wine regions, separated by the Cascade Range, which casts an important rain shadow over much of the area. As such, the vast majority of vines are grown and cultivated in the dry, arid desert-like area in the eastern half of the state, with the western half producing less than one percent of the state's wines where it is considerably wetter. Washington state is famed for producing many of the most accessible wines of the country, with Merlot and Chardonnay varietal grapes leading the way, and much experimentation with other varietals characterizing the state's produce in the twenty-first century.