Sub-locations
| Name | Sites | Samples |
|---|---|---|
| NC | 4 | 11 |
| ND | 151 | 619 |
| NE | 101 | 445 |
| NH | 43 | 132 |
| NJ | 105 | 292 |
| NM | 1287 | 6024 |
| NV | 92 | 72 |
| NY | 239 | 762 |
| OH | 528 | 2413 |
| OK | 204 | 865 |
| OR | 726 | 2890 |
| PA | 359 | 2238 |
| RI | 72 | 321 |
| SC | 47 | 145 |
| SD | 232 | 762 |
| TN | 65 | 344 |
| TX | 388 | 2950 |
| UT | 858 | 3076 |
| VA | 119 | 425 |
| VT | 68 | 259 |
| WA | 706 | 3012 |
| WI | 229 | 1005 |
| WV | 126 | 529 |
| WY | 2623 | 8048 |