Yakima's growth in the 20th century was fueled primarily by agriculture. The Yakima Valley produces many fruit crops, including apples, peaches, pears, cherries, and melons. Many vegetables are also produced, including peppers, corn and beans. Most of the nation's hops, a key ingredient in the production of beer, are also grown in the Yakima Valley. Many of the city's residents have come to the valley out of economic necessity and to participate in the picking, processing, marketing and support services for the agricultural economy.