We sampled the coffee-bean snail, Melampus bidentatus in four habitats (Spartina patens, tall/creekside S. alterniflora, stunted S. alterniflora, and transitional S. patens) in 8 marshes in the northeast U.S. , including the Plum Island Estuary. Overall, snails were larger in the stunted S. alternilfora and transitional S. patens habitats than in S. patens ones. Only 2 snails were found in the tall S. alterniflora. Temperature, relative humidity and other inverts were also measured. These data are published in Johnson and Williams 2017 ( http://onlinelibrary.wiley.com/doi/10.1002/ece3.3291/full ) and refered to as the Regional Study.