In the mid-19th century, a man became rich. Little did he know that it would result in the largest migration of people in U.S. history. Thousands of people were looking to get rich quick and live the American dream. On January 24, 1848, James Marshall found gold coins in the American River at Sutter's Mill in the small port town of San Francisco (Sonneborn). At that time in the United States, America was at war with Mexico. However, just nine days after the great gold discovery, the United States and Mexico signed the Treaty of Guadalupe Hidalgo. The treaty ended the Mexican-American War, and by paying Mexico $15 million, the United States received territories including Nevada, Utah, Arizona, New Mexico, Colorado, Wyoming and California (Sonneborn). In 1848, news traveled so slowly that California residents did not learn of the treaty until August of that year. Communication was also a contributing factor to Mexico selling California to the United States. Had they known about the gold discoveries and the potential economic expansion that could result, Mexico may have been much less likely to enter into the deal with the United States that declared the U.S. Territory of California . Once word of the presence of gold in California spread, thousands of people began to migrate to California. This created a massive demand for mining supplies, shelter, and food, and many new job opportunities appeared (Ketchum). This resulted in the rapid expansion of California as a western United States territory. Although it also had negative aspects, including increased violence, crime, racism, prostitution, and gambling, the California Gold Rush was generally beneficial for expansion of Western society in America. .....with them. In April 1850, they imposed a rate of $20 per month on all non-American miners. The reason was the “privilege of taking from our country the vast treasure to which they have no right.” This caused some miners to retreat to their home countries, but it did not benefit everyone. With the departure of foreign miners, traders who relied on their sales were exposed. This resulted in the tax being removed a year after it was installed (Sonneborn, 59). The primary reason the Gold Rush was overall beneficial to California's expansion was the boom in economic opportunity that arose with the discovery of gold. Soon after groups of men began mining for gold, companies from San Francisco set up shop. They offered clothing, tools and foodstuffs in exchange for gold. They mainly exploited “the miners” (Sonneborn, 67).”