The Checklist of Pennsylvania Mosses lists 443 moss taxa from Pennsylvania, but only 13 from Jefferson County. The authors collected an additional 79 taxa from the county. Mosses of interest include Bryum dichotomum, B. pallens, Dicranodontium denudatum, Helodium elodioides, Philonotis longiseta, Racomitrium aciculare, Schistidium viride, and Tortula obtusifolia. Currently, 92 moss taxa have been verified from Jefferson County, Pennsylvania.