The California Trail was a major overland emigrant route across the Western United States from Missouri to California in the middle 19th century. It was used by 250,000 farmers and gold-seekers to reach the California gold fields and farm homesteads in California from the early 1840s until the introduction of the railroads in the late 1860s. The original route had many branches and encompassed over 5,000 miles (8000 km) of trails. Over 1,000 miles (1600 km) of the rutted traces of the trail remain throughout the Great Basin as historical evidence of the great mass migration westward. Portions of the trail are now preserved by the National Park Service as the California National Historical Trail.