Although Utah is seldom mentioned as a major gold producer it is rated sixth in the United States. Most of the production came as a by product of copper mining. Utah's gold concentrations generally line in the central part of the state in a north to south zone. Most of the gold areas are within an easy drive from Salt Lake City. On the western side of the Oquirrh Range is the world's largest copper mine. It is located in Bingham Canyon and gold has been produced in the same Canyon since 1863. Mining is important to Utah's economy. Commercial placer operations in Utah have been mostly considered unsuccessful, however, in many parts of the state there are large areas of stream and bench gravel that have not been tested. Lack of water in many areas has hampered prospecting efforts.