In January 1848 James W. Marshall, while constructing a sawmill on the American River for the Swiss entrepreneur Johann August Sutter, discovered flecks of gold in the millīs tailrace. Sutter tried to conceal the news, knowing that a gold rush would endanger the little empire he had erected within only 13 years. His farm colony New Helvetica" with large herds of cattle, sheep, and horses covered 5,900 square kilometers. But in May reports of the gold findings reached San Francisco, causing a minor gold rush among Californians. These Americans represented the core of the gold diggers and were called "Argonauts" after Jason and his fellows who searched for the Golden Fleece in ancient Greek mythology.
News of the California gold spread by ship to Hawaii in June and to Oregon and the Atlantic Coast in August. But it was December 5, 1848 before President Polk officially confirmed the discovery of gold in California. Two days later, government agents Losier and Carter arrived in Washington from the gold fields with a tea caddy containing 320 ounces of gold. Put on display at the War Department in Washington, the gold attracted visitors, officials, and reporters, dispelling any remaining doubts about the California gold.
In early 1849 the major gold rush began: people stampeded to California from all over the United States and Europe as well as Mexico, Chile, China, the Sandwich Islands, and Australia. In one year roughly 85,000 people migrated to California. Very soon, metaphors of lunacy or sickness were coined to describe those migrants who seemed to be afflicted by "gold fever."