Harrisburg is a city in Linn County, Oregon, United States.There were 1,318 housing units at an average density of 941.4 per square mile (363.5/km2).17.2% of all households were made up of individuals, and 5.8% had someone living alone who was 65 years of age or older.There were 1,038 housing units at an average density of 649.5 per square mile (250.8/km2).17.6% of all households were made up of individuals, and 6.1% had someone living alone who was 65 years of age or older.