It was George Washington's vision that America would one day become a "granary to the world." Toward that end, he created at Mount Vernon a laboratory for testing and implementing new and more effective farming practices. For example, in the mid-1760's he became one of the first large Virginia planters to switch his main cash crop from tobacco (the traditional staple of the Virginia economy) to wheat. At the same time, he began experimenting with composting and crop rotation, as well as with more efficient designs for such basic farming implements as the barrel seeder and the plow. And because he was convinced that mules were much superior to horses as draft animals, he assumed a pioneering role in introducing the mule to American agriculture.

Perhaps the most interesting of all Washington's farming innovations was a nearly round barn, with 16-sides, designed specifically for thrashing wheat.  This barn was reconstructed at the Pioneer Farm site in 1996 so visitors could truly understand the wonder of this invention.

How did the barn work, and why did Washington see a need for it? Traditionally, wheat was threshed by hand. After harvesting, workers would undertake the slow and backbreaking process of beating the wheat with a flail to break the grain out of the straw. Alternatively, wheat was sometimes "treaded out," or trampled by horses, on open ground.  Although this second method was more efficient than the first, it had the disadvantage of being highly unsanitary -- in that dirt and horse excrement would become mixed in with the grain. Further, with both methods one and two, the grain would be exposed to the vicissitudes of weather throughout the threshing process. So in order to operate more efficiently, reduce loss, and improve the quality of his grain, Washington decided to move the treading process indoors.

Work on the 16-sided barn began in 1792. It took two years for Washington's carpenters to finish the construction. The foundation and first floor of the barn were made of brick, and the second floor, of wood planks. The barn measured 52' in diameter with a 28' central octagonal section (used for storing unthreshed wheat). A 12' wide oak threshing lane encircled the center section. Horses would run around and around within the lane, treading the grain out of the wheat. A farm worker was present to make sure that the horses did not stop running because horses do not urinate or deficate while they are running.  Washington designed the flooring for the barn's treading level so that there were 1 1/2 " gaps between the floorboards. As the horses trod out the grain from the straw, the grain would fall between the gaps to the first floor, where it was gathered up and stored until being taken to the gristmill to be ground into flour.

Although he was in Philadelphia serving as President at the time, Washington carefully supervised the construction of his new barn. He even calculated (correctly) that the number of bricks needed to complete the first floor would be 30,820!