a market garden has a practical upper bound based on this model, but with conventional farming can farm vast areas because access to a direct market is not a requirement. Larger market gardens often sell to such local food outlets as supermarkets, food cooperatives, community-supported agriculture programs, farmers' markets, fresh food wholesalers, and any other higher-volume channels that benefit from buying a range of vegetables from a single supplier, their freshness allowing for a premium over the revenue from the supermarkets and frequently other local suppliers. A larger market garden can by mixed crop production maintain a sales alternative to the wholesale commodity-style channels often used by farms that specialize in high volumes of a limited number of crops. Relying on cities for markets, however, can have drawbacks. For example, in England, south Sussex was famous for growing tomatoes for the London market that were delivered by train. The arrival of railways in the 19th century at first stimulated growth of market gardens in certain areas by providing quick access to the city, but it eventually allowed commuting residents to move there and turn many market garden areas into suburbs. Urban sprawl still eats up farmland in urban regions. Buying the rights to develop farmland from the farmers solved this problem in Suffolk County, New York. Social role In some more affluent countries, including Australia and the United States, market gardening is rated as a high social utility occupation. It is typically taken up by recent immigrant groups for one or two generations, until they can accumulate capital, language and trade skills. The succession of dominant market garden groups in Australia, for example, was – from the early 19th century Anglo-Celtic, people from German-speaking countries, Chinese (after the peak of the gold rushes in mid-late 19th century), then southern European migrants from Italy, Malta and Yugoslavia (before it disintegrated), then southeast Asian migrant and refugee communities following the Vietnam War, such as the Vietnamese and Cambodians. Involvement in a market garden lets immigrant groups who otherwise have few marketable skills apart from their labour, become actively involved in the market economy. Benefits are that it does not rely on education or language, it adapts well to providing work for extended family groups, and in large market growing regions even wider community support networks. Sharing of knowledge and experience within communities reduces risks, and supports a network of other trades such