Where volunteers monitor
Context 19,960 sites across the lower 48 states have usable surveys; most are in IA, NJ, VA.
19,960sites with usable surveys
IA, NJ, VA, MD, MNstates with the most sites
Biological surveys, which the expected-score model learns from, cluster in the mid-Atlantic and upper Midwest. Salt Watch and Nitrate Watch kits spread monitoring much more widely. No map tiles are loaded: the dots are placed by each site's own coordinates, and each opens in Google Maps.