Delaware Township is a township in Northumberland County, Pennsylvania, United States. The population at the 2020 Census was 4,303, a decrease from the figure of 4,489 tabulated in 2010. The Allenwood River Bridge, Hopper-Snyder Homestead, William Kirk House, and Warrior Run Presbyterian Church are listed on the National Regiā¦Delaware Township is a township in Northumberland County, Pennsylvania, United States. The population at the 2020 Census was 4,303, a decrease from the figure of 4,489 tabulated in 2010. The Allenwood River Bridge, Hopper-Snyder Homestead, William Kirk House, and Warrior Run Presbyterian Church are listed on the National Register of Historic Places.