Prospectors who traveled to California to mine for gold in 1849 are called "forty-niners" because of the year in which the first prospectors embarked on their mining journeys: 1849. According to Reference.com, this term originated in the early 1850s and has been used to refer to the prospectors who took part in the California golf rush ever since.
According to the Library of Congress, nearly 100,000 forty-niners traveled to California to search for gold in 1849. These gold-seekers came from all over the world. Many were from the United States, but some were from Australia, New Zealand, Hawaii, China and even Europe. Those who lived overseas traveled to California via established trade routes. Those who came from the Eastern United States traveled across the nation by land to reach the gold coast, as it was called. According to the Library of Congress, some easterners reached California by sailing to Panama, crossing Panama by foot, then sailing to California via the Pacific Ocean. Unfortunately for the forty-niners, very few ever found gold or struck it rich in California. Some forty-niners were able to make livings for themselves by providing the other miners with goods and services. Thus, towns were established by the forty-niners, and the population of California increased rapidly.