Locations
| Name | Sites | Samples |
|---|---|---|
| Arenac County | 1 | 1 |
| Argentina | 187 | 580 |
| Armenia | 8 | 19 |
| Armstrong County | 1 | 1 |
| Ascension Parish | 2 | 11 |
| Ashley County | 4 | 13 |
| Assumption Parish | 1 | 4 |
| Atascosa County | 6 | 28 |
| Atkinson County | 1 | 1 |
| Atlantic County | 2 | 5 |
| Atoka County | 14 | 34 |
| Auglaize County | 1 | 1 |
| Augusta County | 4 | 8 |
| Austin County | 4 | 9 |
| Australia | 1554 | 4529 |
| Austria | 80 | 285 |
| Autauga County | 3 | 3 |
| Avoyelles Parish | 5 | 20 |
| Azerbaijan | 2 | 9 |
| Baldwin County | 11 | 87 |
| Baldwin County | 2 | 2 |
| Ballard County | 2 | 23 |
| Baltimore County | 4 | 7 |
| Bandera County | 1 | 2 |
| Barber County | 3 | 6 |
| Barbour County | 3 | 5 |
| Barnes County | 1 | 1 |
| Barnwell County | 5 | 7 |
| Bartow County | 17 | 45 |
| Bastrop County | 8 | 19 |