The 2.5 story log mill on stone foundation was built by Robert McCormick, Cyrus McCormick's grandfather who had moved to the area from Cumberland County, Pa. in 1779. Robert, with his wife and 5 children, settled on 450 acres of land on the Rockbridge-Augusta Co. boudary. The farm or community that developed was called Walnut Grove and consisted of a blacksmith shop, grist mill, manor house and various other out buildings associated with early self-sufficient farmsteads/plantations.

The mill used a 17' overshot wheel to turn a quite complex system of mechanisms to produce flour and grind feed. Marl Creek was impounded about 525' upstream of the mill site and two run of stone, one for wheat and the other for corn and barley, were powered with water from the dam, through a smooth penstock to the second level of the mill to feed the overshot wheel.

The mill operated into the late 1800's and like most mills, fell into a time of idleness and non-upkeep. The mill was renovated in the 1930's. In 1954, the property was deeded to the Virginia Polytecnic Instutute. During this time, the old wooden axle for the water wheel was replaced with a metal axle. Agricultural Research & Extension Center.

In 1993, a new shingle roof was put on the mill and the water wheel again rebuilt, using a partial grant from Spoom. Hugh Trumbull Adams, a descendant of the McCormicks, financed mill, milldam, and raceway stabilizations in 1997. The mill is currently restored to the mid 1800's style of log mill and is a fully functional part of the Shenandoah Valley

Robert's grandson, Cyrus McCormick took his grandfather's dabbling in inventions of mechanical harvesters a step further in 1831 when he demonstrated his new reaper at the farm. Then only 22 years old, he had irreversably changed the concept of farm crop harvesting for future generations. His reaper led to the formation of the International Harvester Corporation.