Congressman Kelly Armstrong represents the entire state of North Dakota in the U.S. House of Representatives. North Dakota is one of seven states with only one district, otherwise known as an At-Large District.
If you are interested in browsing district-specific population statistics, you can look up Census data for North Dakota.
The U.S. Geological Survey has provided this detailed map of North Dakota (seen below). Please click the image to access a high-resolution version.