In Broadhorns! Early Trade on The Mississippi the players take the role of merchants based in St. Louis, financing cargo expeditions down the Mississippi River during the early part of the 19th century.

The game is played over the course of a year through the varying seasons, each presenting its own challenge. During the game, the players will finance a number of trips. With each one they will need to obtain a boat (known as a broadhorn or flatboat) and purchase cargo. The player receives a higher return for their cargo the farther down the Mississippi they travel. Some of the cargo is perishable so time is of the essence. In addition, there are travelers willing to pay for passage down the Mississippi.