The U.S.-Mexican War in 1846 marked the end of the Mexican era of California’s history. This conflict produced notable military resistance and while some died to prevent the American takeover, others welcomed the change of sovereignty. They had hopes that their economic prosperity and political liberties would be secure under the American constitution and guarantees of the Treaty of Guadalupe Hidalgo. These hopes would soon give way to the realities of massive immigration of Americans into California during the Gold Rush.
The Gold Rush influenced the fortunes of millions of men and women, from the lowly miners who never struck it rich and who abandoned their families back east, to the fabulously wealthy entrepreneurs such as William Ralston, George Hearst, and Leland Stanford, who helped shape the economic future of the state. The Gold Rush changed the world’s supply of gold so drastically that silver quickly became devalued as a currency and the gold standard became the norm of industrialized countries into the 20th century. As can be surmised by the history of this period, the Gold Rush inaugurated a large-scale exploitation of the natural environment in America. As forests were devastated, rivers polluted, and mountains leveled, Americans were slow to realize that they were ravaging a non-renewable resource. This realization did not come until the last part of the following century. Contemporary historians believe that the Gold Rush was important primarily because of its consequences for families and social values. The tens of thousands of Anglo Americans who left their families in the east created broken homes and, for many, broken lives when their husbands did not return or came back beaten and impoverished. In California, the Gold Rush had a mixed effect on morality. For some, it reinforced values of hard work, democracy, and community. For others, it created a “get rich quick” mentality of speculation, lawlessness, and isolation. For the Indians, the Mexicans, and the Chinese, the Gold Rush created an inhospitable society that had to be negotiated with great care.
Ultimately, the U.S.-Mexican War and the California Gold Rush were watershed events, not only in the development of the West but in the history of the United States more generally. Coming together, they shaped the future of the nation and created new directions for California. New economic forces and the blending of cultures and peoples begun in these years provided the dynamic energies that would have a worldwide influence.