Up until the middle of the 19th century, wheat was the primary crop grown in California. The favorable climate allowed the beginning of the intensive cultivation of certain fruits, vegetables and flowers. In the East Coast of the United States a strong demand for these products existed. However, the supply of these markets became possible only with the completion of the transcontinental railroad. Just as with the railway construction, there was a dire manpower shortage in the expanding Californian agriculture sector, so the white landowners began in the 1860s to put thousands of Chinese migrants to work in their large-scale farms and other agricultural enterprises. Many of these Chinese laborers were not unskilled seasonal workers, but were in fact experienced farmers, whose vital expertise the Californian fruit, vegetables and wine industries owe much to this very day. Despite this, the Chinese immigrants could not own any land on account of the laws in California at the time. Nevertheless, they frequently pursued agricultural work under leases or profit-sharing contracts with their employers.