Fort Benton is a city in and the county seat of Chouteau County, Montana, United States. A portion of the city was designated as a National Historic Landmark District in 1961. The population was 1,594 at the 2000 census. Established by European-Americans Auguste Chouteau and Pierre Chouteau, Jr. of St. Louis in 1847 as the last fur trading post on the Upper Missouri River, the fort became an important economic center. For 30 years, the port attracted steamboats' carrying goods, merchants, gold miners and settlers, coming from New Orleans, Memphis, St. Louis, Hannibal, Bismarck, Kansas City, etc. As the terminus for the 642-mile-long Mullan Road, completed by the US Army in 1860, Fort Benton was part of the overland link between trade on the Missouri River and the Columbia River, at Fort Walla Walla, Washington. Twenty thousand migrants used the road in the first year to travel to the Northwest. It became an important route for miners from both directions going into the interior of Idaho. With the decline of the fur trade, the American Fur Company sold the fort to the US Army in 1865, which named it for Senator Thomas Hart Benton of Missouri. A town had grown up around it that surpassed the military presence. Besides being one of the most important ports on the Missouri-Mississippi river system, Fort Benton was once the "World's Innermost Port". Its importance in trade was superseded by the construction of transcontinental railroads in the late 19th century. In 1867 Fort Benton was the site where Union General Thomas Francis Meagher, then acting governor of Montana Territory, fell overboard from his steamboat and drowned in the river; his body was never recovered.