Lichens and bryophytes are phylogenetically unrelated organisms that, however, share important ecological traits, such as their poikilohydric nature, lack of a cuticle, and largely atmospheric nutrient uptake. Because of these characteristics, lichens and bryophytes are among the most sensitive indicators of environmental change, including but not limited to N-, S-, metallo- and organo-deposition, UV radiation, and ecological continuity. In addition, they are dominant organisms in arctic-alpine and desert habitats, which are the vanguard of climate change. Altogether ca. 5.4 million specimens collected over the past 200+ years are housed in US herbaria. Of these ca. 1.6 million have been databased and are searchable through two national portals. Of the 3.8 million specimens not databased, ca. 2.4 million are from North America. Herein we plan to image ca. 2.3 million North American specimens from over 60 collections representing well over 90% of the remaining North American specimens from Canada, the United States and Mexico. This involves over 95% of the U.S. institutions known to hold at least 500 specimens. Images of labels, annotations, specimen notes, and example specimens will be photographed, barcoded and made centrally available online through the two consortia web sites. Printed labels will be transcribed using specifically optimized Optical Character Recognition, Natural Language Processing, and geo-referencing procedures. Subsequent completion of transcribing and data proofing will be handled by the originating collections utilizing online resources. Hand written labels will be fully transcribed by the originating collections, often using networks of trained volunteers as well as collection staff. Although all North American specimens will be imaged for transcription each collection will initially place priority on collections of their main collectors, as duplicates found in other collections are likely to occur in these records. Duplicate records, such as prevalent exsiccate, can then be exchanged with only one institution handling the transcribing. Edited data will be available from the central database via standard exchange protocols (DarwinCore, TAPIR, DiGIR) to the home institution as well as larger portals, e.g. GBIF, IPNI, Species 2000, or an ADBC HUB. Upon completion of the project collection databases will be maintained by the institutions holding the specimens and synchronized with the national portals. This project will develop particularly efficient workflows for digitizing lichen and bryophyte specimens taking advantage of efficiency of scale and exploiting proven automation technology. The specific goal is to provide high quality data to address how species distributions change with regards to major environmental events across time and space, both historically and into the future via informed scenario building and modeling. Large scale distribution mapping will elucidate regions where such changes are imminent and may have substantial impact and will inform proactive initiatives to prevent them. It will also allow identifying biodiversity hotspots and areas of sampling bias with understudied areas in need of further sampling. Availability of the entire bryophyte and lichen collections online will greatly accelerate taxonomic revisions and will thus contribute substantially to cataloging organismic diversity on our planet by fostering global collaborations. The national bryophyte and lichen web portals already have the functionalities for providing user defined virtual floras including specimen keying, distribution mapping, and species descriptions and images based on searchable collections records. These portals are already a major resource to scientists, public land managers, students, and amateur enthusiasts. The additional specimen records will geographically expand the applicability of the virtual floras. The outreach component of this proposal will build and enhance a vibrant national volunteer community with the approach comparable to the successful British program ‘Herbaria@Home’ and will provide online seminars, extensive online training materials, and local workshops and field trips. Database training will be provided to participating collections as needed.