Twelve new diatom species are described from remote locations in the western United States: Cymbella blinnii sp. nov., Cymbopleura maggieae sp. nov., Encyonema drakei sp. nov., E. pentoniae sp. nov., E. willeyorum sp. nov., Frustulia esandalliae sp. nov., Gomphonema darwinii sp. nov., G. evolutionensis sp. nov., Muelleria agnellus sp. nov., M. spauldingiae sp. nov., M. tetonensis sp. nov., and Navicula harmoniae sp. nov. Descriptions are supported by LM images showing size diminution in the type populations and by SEM images. Type populations of the new species are from California (3 species), Colorado (3), Montana (2), Oregon (2), Washington (1), and Wyoming (1). All of the type materials for these new species were collected by unpaid citizen volunteers. This paper reviews other new species and significant new distribution records produced by volunteer collections. It also discusses the process of engaging citizen volunteers in diatom collection and the value of citizen collections in building diatom herbaria, in cataloging diatom biodiversity, and in expanding our knowledge of diatom biogeography, especially in remote regions with difficult access.