Old Washington was platted along Zane’s Trace in 1805 by the brothers George and Henry Beymer. Within two years, twelve log dwellings had been built, making it the oldest settlement in Guernsey County. Originally known as New Washington, it was generally called Beymerstown because the Beymers were its founders. On February 10, 1829, two years after the National Road was completed through the town, it was incorporated as Washington, with the prefix "New" dropped after the discovery that another Ohio town of a similar name already existed. Later, after confusion with Washington Court House, the postal department requested that Washington in Guernsey County change its name, and the prefix "Old" was reluctantly added because it was an older town. Old Washington grew rapidly after the National Road was built, reached its peak population in 1850, and, because of a lack of growth after the Civil War, survived as an excellent example of a 19th century National Road town.