The nine U.S Census Bureau Census Divisions¹ (New England, Middle Atlantic, East North Central, West North Central, South Atlantic, East South Central, West South Central, Mountain, Pacific) are the geographical areas represented in the NIS. Which States are in the NIS varies by data year.

1. Division 1 (New England): Maine, New Hampshire, Vermont, Massachusetts, Rhode Island, Connecticut
2. Division 2 (Mid-Atlantic): New York, Pennsylvania, New Jersey
3. Division 3 (East North Central): Wisconsin, Michigan, Illinois, Indiana, Ohio
4. Division 4 (West North Central): Missouri, North Dakota, South Dakota, Nebraska, Kansas, Minnesota, Iowa
5. Division 5 (South Atlantic): Delaware, Maryland, District of Columbia, Virginia, West Virginia, North Carolina, South Carolina, Georgia, Florida
6. Division 6 (East South Central) Kentucky, Tennessee, Mississippi, Alabama
7. Division 7 (West South Central) Oklahoma, Texas, Arkansas, Louisiana
8. Division 8 (Mountain) Idaho, Montana, Wyoming, Nevada, Utah, Colorado, Arizona, New Mexico
9. Division 9 (Pacific) Alaska, Washington, Oregon, California, Hawaii

Beginning with the 2012 NIS, hospital state (HOSPST) is no longer available, and the NIS is stratified by Census Divisions rather than Census Regions.