Fort Benton is a city in and the county seat of Chouteau County, Montana, United States. Established in 1846, Fort Benton is the oldest every time occupied agreement in Montana. Fort Benton was the most upstream navigable port on the Mississippi River System, and is considered “the world’s innermost port”.

The city’s marina area, the most important aspect of its 19th century growth, was designated the Fort Benton Historic District, a National Historic Landmark, in 1961.

The population was 1,449 at the 2020 census.

Established in 1846 by Alexander Culbertson, who worked for Auguste Chouteau and Pierre Chouteau, Jr. of St. Louis, the indigenous fort was the last fur trading post upon the Upper Missouri River, the fort became an important economic center. For 30 years, the harbor 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 United States Army in 1860, and at the head of navigation of the Missouri River, Fort Benton was share of the overland colleague between trade on the Missouri 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, and north to Canada. Steamboat travel to Fort Benton from St. Louis, Missouri, helped broadly fuel the spread of the American West between 1860 and 1890, when it was supplanted by railroad transport. The river was an important route for miners to the newly discovered gold fields of southern Montana at what became Bannack and Virginia City coming on in 1862, and Helena, beginning in 1865.