Jacob likely commanded a Conestoga Wagon, very similar to this example:
The Conestoga Wagon was said to be built in 1717 and was named for Conestoga Township, Lancaster, PA--the same area Jacob Hoover was from. The wooden and iron-rimmed wagons pulled by horses or mules, were built with a curved floor in order to keep supplies from shifting during travel on rough or uneven surfaces. Wagons were usually about 18 feet long, 11 feet high, 4 feet wide, and could haul up to 12,000 pounds of supplies or men. In order to keep the wagon from sinking in water, the seams between the boards were filled with tar.