The Conestoga was a heavy freight wagon, and very few passed over the Oregon Trail because of the rough terrain. From 1841-1859, thousands of emigrants traveled this trail in wagons similar to the prairie schooner. The army also relied on wagon transport, with hundreds of six mule U.S. Army wagons moving supplies for combat units in the field while commercial freighters supplied forts and base camps. Freighters used still larger and heavier wagons to haul the food, hardware, and machinery needed in western settlements. Freight moved about fifteen miles a day at as much as 25¢ per pound to the Rockies. Tracks on the hillside were left by wagons that passed here more than a century ago.