A computer search of the National Register of Historic Places discloses the following inventory of round/polygonal barns (by state). Please note that these are only approximations since not all "round" barns are listed in the Register due to not having been nominated or being ineligible because of their deteriorated state. For example, in SD there were originally 44 round/polygonal/centric barns of which 36 existed in 1995, but only seven were on the Register.
| DE 1 | GA 1 | IA 49 |
| IL 18 | IN 32 | KS 2 |
| ME 1 | MN 5 | MT 1 |
| ND 7 | NE 2 | NY 4 |
| OH 6 | OK 2 | OH 1 |
| PA 2 | SD 7 | WA 1 |
| WI 5 | WV 6 |
IA, IL, IN, ND, and SD have statewide National Register Multiple Property nominations; a list of these barns is available from the respective State Historic Preservation Office. OH has "Round Barns in the Black Swamp of Northwest Ohio", and WI has a similar list entitled "Centric Barns in Rock County".
Note: These numbers were gathered from the National Register database and should be treated as approximations. Also, new nominations are processed all the time so the numbers will hopefully increase. Information supplied by Stephanie Ahrendt.