Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Copper mining in Arizona, a state of the United States, has been a major industry since the 1800s. In 2007 Arizona was the leading copper-producing state in the US, producing 750 thousand metric tons of copper, worth a record $5.54 billion. Arizona''a copper production was 60% of the total for the United States. Copper mining also produces gold and silver as byproducts. Byproduct molybdenum from copper mining makes Arizona the nation''s second-largest producer of that metal. Although copper mineralization was found by the earliest Spanish explorers of Arizona, the territory was remote, and copper could not be profitably mined and shipped. Early Spanish, Mexican, and American prospectors searched for gold and silver (see Silver mining in Arizona), and ignored copper. It was not until the completion of the Southern Pacific Railroad in 1876 that copper became broadly economic to mine and ship to market.