Native Americans had a long tradition of vegetable cultivation when the first European explorers arrived in the 16th century. European settlers established small gardens near their dwellings that included not only vegetables but medicinal herbs. Common crops included turnips, cabbage, peas, corn, pumpkins and squash. Through the 18th and early 19th centuries, American diets consisted mostly of grains, meat, fish and game. Vegetables were considered a luxury item, seldom consumed by the common man. As cities enlarged in the 1820s and 1830s, demand for fresh vegetables increased and market gardening became a profitable profession. These farms cultivated a variety of high value and very perishable vegetables. The crops were sold at local markets. By 1850, truck farming came into vogue. Truck farms differed from market gardens in that they were located at a greater distance from their markets where land was less expensive. Truck farmers grew only a few vegetable crops on much larger acreage, usually less valuable and less perishable commodities than those found in market gardens. Their success was due to gains in transportation, first in railroads and later in trucking. Over time, truck farms located in areas of ideal climate and long seasons, most notably the Southeast and California, with large processing acreage in the upper Midwest. Vegetable production in the US continues to be a mix of these methods, local, diversified farms selling directly to consumers and large farms in distant areas producing low cost product for wholesale.