NDSU is part of the North Dakota University System. It is one of the largest universities in the state of North Dakota. The university also operates North Dakota's agricultural research extension centers distributed across the state on 18,488 acres (75 km2). In 2015, NDSU's economic impact on the state and region was estimated to be $1.3 billion a year according to the NDUS Systemwide Economic Study by the School of Economics at North Dakota State University. In 2016, it was also the fifth-largest employer in the state of North Dakota.