Fort Carroll and its trading post were established in 1874 by the Diamond R Transportation Company to move freight and passengers from the docks on the Missouri River to Helena, Montana. The post was named for Matthew Carroll, one of the company’s founders. The plan was to replace Fort Sheridan (also called Kerchival City Post) and challenge Fort Benton as a transportation and supply center. The steamboat landing was also called Carroll Landing. The 7th U.S. Infantry garrisoned the post in the summers of 1874 and 1875. The town of Carroll, Montana, soon sprung up at the landing. It no longer exists today.
Freight destined for the goldfields in Helena left St. Paul, Minnesota, on the newly constructed Northern Pacific Railroad for Bismark, North Dakota, where the rails ended. It then came by steamboat up the Missouri River to the newly built Fort Carroll and then overland by wagon to Helena. Supplies and materials for Fort Maginnis, Montana, followed the same route in 1880-81, and then overland to Fort Maginnis on the Carroll Trail. At some point, the site was renamed Rocky Point.
The landing was situated in a stand of cottonwoods whose banks were about a foot above the water. Joseph Kipp had a trading post here from 1880 to 1882, which consisted of a trade store, storehouse, and residence. Both the town and fort were abandoned in 1882.
It was located about 30 miles above the mouth of the Musselshell River on the Missouri River in present-day Fergus County.