According to the United States Census Bureau, the city has a total area of 3.4 square miles (8.8km2), all land. The United States Census Bureau lists Grafton's population as 4,284. Grafton is a city in Walsh County, North Dakota in the United States. It is the county seat of Walsh County. The 2010 Census found Grafton home to 4,284 residents, making it the thirteenth largest city in North Dakota. Grafton was founded in 1881.