Mesilla Valley is an American Viticultural Area (AVA) located in the Mesilla Valley landform that extends along the Rio Grande River encompassing an area from the vicinity north of Las Cruces, New Mexico within Dona Ana County on a 50-mile (80 km) north-south axis toward the Mexican border, across the state border to El Paso County, Texas and the vicinity of El Paso. It was established as the nation’s 100th AVA on February 14, 1985 by the Bureau of Alcohol, Tobacco and Firearms (ATF), Treasury after reviewing the petition submitted by Mr. George Newman, President of the Las Cruces Chapter of the New Mexico Wine and Vine Society, proposing a viticultural area located in New Mexico and Texas named "Mesilla Valley." It was also the initial designated viticultural area in both states of New Mexico and Texas. Cabernet Sauvignon, Zinfandel and Syrah are the most important grape varieties planted there. The plant hardiness zones are 8a and 8b. The climate in the Mesilla Valley is dry and hot.