What began as an informal network of trails created by Native Americans to trade and hunt was expanded by the expeditions of prominent explorers, including Meriwether Lewis, William Clark, and John Jacob Astor to become the migration paths of America’s settlers and later some of the roads and highways that traverse the country today. Early traders, mapmakers, and surveyors provided descriptions and rudimentary maps to people living in the East that piqued the public imagination. Fur traders, such as Jedediah Smith and Kit Carson, later expanded American settlers' knowledge of the Western half of the continent by sharing experiences from their trapping expeditions. Missionaries used this information to venture into the northwest to found churches in the 1830s. Large-scale migration into the Oregon Territory began in 1840, when the trail, which would become known as the “Oregon Trail,” was still faint and maps were scarce.