January, 1848. Americans had begun coming into California several years previously and a colony was already established near where Sacramento now stands. Marshall was constructing a saw mill some forty miles distant on the west slope of the Sierra Nevada and on the south fork of the American River, which is a tributary of the Sacramento River. He observed some glistening particles in the gravel washed by the waters of the mill, and at once identified them as gold. A few days later he went down to the settlement on the Sacramento River to tell of his discovery to Colonel Sutter, with whom he was associated in the erection of the mill.
In spite of all efforts to keep the discovery from public notice the news spread; the people in the neighborhood made further search, and soon found gold to be abundant in many other places. The excitement rapidly increased, and by the summer of 1848 several thousand people were already mining in the neighborhood. San Francisco, then a small village, was almost depopulated in the sudden exodus for the gold fields. By autumn the news had reached the eastern states and foreign countries, and history has never before or since recorded such a mad rush of different races of people to a common center, overcoming difficulties that would have been considered almost insurmountable had it not been for the idea of gold, limitless gold, lying there in the ground to be dug up by the first who came. Among the earliest to arrive from the outside were Mexicans, Peruvians, Chileans and Chinese, as they could reach the region quickly by sea; but the great tide of immigration that soon came from the eastern states, around Cape Horn, across the Isthmus of Panama and over the emigrant trail, soon placed the Americans in the majority, and by the end of 1849, there were nearly 100,000 miners on the ground. Thousands of others died on the way, from exposure and starvation, from heat and thirst in the desert, from attacks by the Indians and from cholera, which killed many along the trail in 1849.
In the meantime one discovery of gold rapidly followed another in the gravels of the many rivers and creeks that run down the west slope of the Sierra Nevada, and miners were soon working for over 150 miles along the mountains. Since then the range of the gold discoveries has spread over wider limits, reaching from the northern to the southern boundary of the state, but the larger part has come from the region worked in the early days, extending from Mariposa County on the south to the Feather River on the north. Fortunes were made quickly and lost with equal facility, but in the meantime a new region was being developed with wonderful rapidity and the western progress of the United States had, as if by a single jump, been advanced over fifteen hundred miles, from the Missouri River to the Pacific Ocean. Throughout the world, the discoveries in California stimulated interest