The first great wave of immigration from Asia was brought by the building of Transcontinental Railroad and also by California Gold Rush. California Gold Rush started after James W. Marshall discovered gold in 1848 in the American River at Sutter’s Mill in Coloma, California, in the foothills of the Sierra Nevada. Not long after, gold was discovered in the Feather and Trinity Rivers, also located northeast of Sacramento. The first people to rush the gold fields were those already living in California, but as word slowly got out, people from other parts of the United States as well as from foreign countries (Mexico, Chile, Peru, Pacific Islands, Australia, New Zealand, China and other parts of Asia, and some from Europe, mainly France) arrived. It is estimated that by 1855 some 300,000 people had streamed into California hoping to strike it rich. The port town of San Francisco went from a population of about 1,000 in 1848 to become the eighth largest city in the U.S. in 1890, with a population of almost 300,000. Several decades later, a similar gold rush broke out in the Klondike region. The Klondike Gold Rush consisted of the arrival of prospectors to the Klondike region of Canada as well as Alaska. Over 100 000 people set out on the year long journey to Klondike, with less than one third ever finishing it. Only a small percentage of the prospectors found gold and the rush was soon over.
Popular attention is focused on the Western United States in the second half of the 19th century, a period commonly called the Old West, or the Wild West. A more complex term, however, is the American Frontier covering the geography, history, folklore, and cultural expression of life of American expansion since first English colonial settlements untill admission of the last mainland territories as states in 1912. The term Wild West frequently exaggerates the romance and violence of the period and is easily associated with Indian wars, cowboys, wagon trains, saloons and banditry.