Mexico, Idaho, Montana, and South Dakota (by 1864). The discovery of the Comstock Lode, containing vast amounts of silver, resulted in the Nevada boomtowns of Virginia City, Carson City, and Silver City. The wealth from silver, more than from gold, fueled the maturation of San Francisco in the 1860s and helped the rise of some of its wealthiest families, such as that of George Hearst. The Oregon Trail To get to the rich new lands of the West Coast, there were three options: some sailed around the southern tip of South America during a six-month voyage, some took the treacherous journey across the Panama Isthmus, but 400,000 others walked there on an overland route of more than 2,000 miles (3,200 km); their wagon trains usually left from Missouri. They moved in large groups under an experienced wagonmaster, bringing their clothing, farm supplies, weapons, and animals. These wagon trains followed major rivers, crossed prairies and mountains, and typically ended in Oregon and California. Pioneers generally attempted to complete the journey during a single warm season, usually for six months. By 1836, when the first migrant wagon train was organized in Independence, Missouri, a wagon trail had been cleared to Fort Hall, Idaho. Trails were cleared further and further west, eventually reaching the Willamette Valley in Oregon. This network of wagon trails leading to the Pacific Northwest was later called the Oregon Trail. The eastern half of the route was also used by travelers on the California Trail (from 1843), Mormon Trail (from 1847), and Bozeman Trail (from 1863) before they turned off to their separate destinations. In the "Wagon Train of 1843", some 700 to 1,000 emigrants headed for Oregon; missionary Marcus Whitman led the wagons on the last leg. In 1846, the Barlow Road was completed around Mount Hood, providing a rough but passable wagon trail from the Missouri River to the Willamette Valley: about 2,000 miles (3,200 km). Though the main direction of travel on the early wagon trails was westward, people also used the Oregon Trail to travel eastward. Some did so because they were discouraged and defeated. Some returned with bags of gold and silver. Most were returning to pick up their families and move them all back west. These "gobacks" were a major source of information and excitement about the wonders and promises—and dangers and disappointments—of the far West. Not all emigrants made it to their