Constructed in approximately 1828, the National Road S-Bridge in Guernsey County, Ohio, stands as a remarkable monument to early 19th-century American transportation engineering. Located near Old Washington, this historic structure is composed of locally quarried, roughly dressed sandstone, masterfully laid to form a durable, single-arch span over a tributary of Salt Fork Creek. Its distinctive "S" shape was a practical engineering solution common to the era, designed to cross the waterway at a perpendicular ninety-degree angle-thereby minimizing the span length and reducing construction costs-while still smoothly aligning with the diagonal trajectory of the road on either side. This layout required immense skill from pioneer stonemasons, who had to construct complex, curving wing walls to transition travelers safely across the creek.

Historically, the S-Bridge is highly significant for its direct association with the National Road (also known as the Cumberland Road), the nation's first federally funded highway. Built to connect the Eastern Seaboard with the rapidly developing Northwest Territory, the National Road served as the primary artery for westward migration, commerce, and communication in the early-to-mid 1800s. By facilitating the steady flow of pioneer wagons, stagecoaches, and livestock, infrastructure like this Guernsey County bridge played a pivotal role in the economic integration and physical expansion of the United States. Today, the bridge is celebrated as one of the few surviving and best-preserved examples of its type, representing a bygone era of civil engineering and the craftsmanship that helped shape the American Midwest.