During the War of 1812, in 1813, the company's officers sold its assets to their Canadian rivals, the North West Company, which renamed the site Fort George. The fur trade remained under British control until U.S. pioneers following the Oregon Trail began filtering into the town in the mid-1840s. The Treaty of 1818 established joint U.S. – British occupancy of the Oregon Country. Washington Irving, a prominent American writer with a European reputation, was approached by John Jacob Astor to mythologize the three-year reign of his Pacific Fur Company. Astoria (1835), written while Irving was Astor's guest, promoted the importance of the region in the American psyche. In Irving's words, the fur traders were "Sinbads of the wilderness", and their venture was a staging point for the spread of American economic power into both the continental interior and outward in Pacific trade. In 1846, the Oregon Treaty divided the mainland at the 49th parallel north, making Astoria officially part of the United States. As the Oregon Territory grew and became increasingly more colonized by Americans, Astoria likewise grew as a port city near the mouth of the great river that provided the easiest access to the interior. The first U.S. post office west of the Rocky Mountains was established in Astoria in 1847 and official state incorporation in 1876. Astoria attracted a host of immigrants beginning in the late 19th century: Nordic settlers, primarily Swedes, Swedish speaking Finns, and Chinese soon became larger parts of the population. The Nordic settlers mostly lived in Uniontown, near the present-day end of the Astoria–Megler Bridge, and took fishing jobs; the Chinese tended to do cannery work, and usually lived either downtown or in bunkhouses near the canneries. By the late 1800s, 22% of Astoria's population was Chinese. Astoria also had a significant population of Indians, especially Sikhs from Punjab; the Ghadar Party, a political movement among Indians on the West Coast of the U.S. and Canada to overthrow British rule in India, was officially founded on July 15, 1913, in Astoria. 20th and 21st centuries In 1883, and again in 1922, downtown Astoria was devastated by fire, partly because the buildings were constructed mostly of wood, a readily available material. The buildings were entirely raised off the marshy ground on wooden pilings. Even after the first fire, the same building format was used. In the second fire, flames spread quickly again, and the