BISON recently published the dataset of the USGS North American Bird Phenology Program, part of the USA-National Phenology Network. This was a network of volunteer observers who recorded information on first arrival dates, maximum abundance, and departure dates of migratory birds across North America. Active between 1880 and 1970, the program was coordinated by the U.S. government and sponsored by the American Ornithologists’ Union. It exists now as a historic collection of six million migration card observations, 1,034,866 of which were digitized here, including 537 unique taxa.