Name Sites Samples
Abbeville County 2 5
Adams County 7 17
Adams County 1 1
Addison County 23 77
Aiken County 16 78
Aitkin County 6 11
Alachua County 6 71
Alamance County 5 7
Albania 4 5
Albany County 2 2
Albemarle County 2 21
Alberta 4 7
Alcorn County 1 2
Alger County 8 13
Algeria 0 0
Allegany County 1 1
Alleghany County 1 1
Alleghany County 1 1
Allen County 1 1
Allendale County 5 40
Amherst County 1 9
Amite County 2 9
Anderson County 2 11
Anderson County 1 3
Anderson County 9 42
Andrew County 1 2
Andrews County 2 4
Anoka County 3 9
Anson County 1 16
Aransas County 3 11