The farm originally covered a plot of land of with buildings centered on a scant five acres. On the farm eight out of the nine original buildings are still standing, many of which have been renovated since the farm was created in 1822. The eight existing buildings include a grist mill, blacksmith shop, slave quarters, carriage house, manor house, smoke house, schoolroom, and housekeeper's quarters . In the original construction of the farm there was also an ice house which was demolished in the 1960s. Each of these different buildings played a specific role in the daily routine of the Cyrus McCormick farm. The grist mill, built prior to 1800, was used to grind wheat for flour. The blacksmith shop was used to build and repair all the farm implements needed by the McCormick family and was where Cyrus McCormick engineered his reaper. Slave quarters served as the home for the nine slaves that the McCormick family owned. Furthermore, the carriage house was used as a garage for the carriages and other wheeled vehicles. The manor house is centrally located on the farm and was constructed out of brick in 1822, making it the first building on the McCormick farm . Behind the brick manor house was the smoke house where meat was dried and smoked in order to preserve the meat through the winter. Drying and smoking the meat prevented spoiling to occur, as was necessary because refrigeration was not introduced until the late 19th century. The McCormick family also maintained a school on their property so that the neighboring children may receive an education. Currently, the schoolroom has vintage textbooks, toys, and other school supplies dating from the 1830s . The farm remained in the McCormick family up to the year 1954, before being donated to Virginia Tech as an agricultural center and Farm Memorial.
The significance of the McCormick Farm at Walnut Grove is that it is the birthplace of the mechanical reaper, the predecessor to the combine. Cyrus McCormick reportedly designed, built, and tested his reaper all within six weeks at Walnut Grove, although the design may have been merely an improvement upon the similar device developed by his father and his brother Leander over 20 years. Shortly after constructing his first reaper he went on to harvest his first crop with the reaper later that year. After building his first reaper, Cyrus constantly went back to the drawing board to revise and improve his basic design, coming out with new models almost every decade. Cyrus McCormick moved his base of operations from Rockbridge County, Virginia to Chicago, Illinois in 1847 because of the fertile prairie soil in the Heartland. In 1859, Cyrus Hall McCormick was joined by his brother Leander James McCormick to form the company Cyrus H. McCormick and Brothers . By the turn of the century, McCormick's company had built a primitive combine, which could harvest grain much faster and cheaper than McCormick's older reapers. Because of McCormick's efforts in making harvesting grain easier and inventing the reaper, his invention allowed farmers the world over harvest grain faster and cheaper than ever before. Prior to inventing the reaper, farmers could only harvest 1/2 an acre a day; after the reaper was invented, farmers could harvest 12 acres a day. By being able to harvest 12 acres a day versus 1/2 acres a day, farmers were able to conserve money by using less manual labor. The mechanical reaper did not require a person to toil all day to harvest crops. Instead, a farmer merely needed to operate the machine and the reaper would do the rest of the work. His work in mechanical reapers and harvesting techniques allowed farmers to cultivate plots of land bigger than ever thought possible.
It was declared a National Historic Landmark in 1964.