Alexander Culbertson established Fort Benton in 1846 as an American Fur Company trading post. The remote settlement prospered in the 1850s, but it was not until the following decade that it truly boomed. The arrival of the steamboat Chippewa in 1859 opened a new era of trade at the World's Innermost Port, carrying buffalo robes and other furs downriver to St. Louis, and three years later transporting the far more valuable gold coming from the mining camps of southwestern Montana. At its height in 1867, thirty-nine steamboats tied up at the levee, unloading supplies and passengers bound for the gold fields. Saloons, hurdy-gurdy houses, and other businesses served a cosmopolitan and transient population, and the streets were crowded with people from across North America, Europe, and Asia, making it a wide-open town. By 1870 the boom had collapsed, but Fort Benton briefly revived when merchants began freighting supplies over the Whoop-up Trail to Royal Canadian Mounted Police forts north of the border. Because of this rich and colorful history, Fort Benton became a National Historic Landmark on the upper Missouri River.