Bumble bees provide important pollination services in managed and natural ecosystems and their reported decline in North America and Europe is expected to have serious ecological ramifications. Unfortunately, evidence for bumble bee declines in North America remains largely anecdotal, limiting conservation efforts. The Illinois Natural History Survey insect collection has an extensive bumble bee collection, with records of species diversity and distribution in Illinois dating back to the 1890’s. Our study extensively surveyed bumble bees across Illinois using collection-based (for permanent deposition) and non-destructive sampling methods (catch, ID, and release). Current distribution and species diversity in Illinois were compared to two time periods for which we have the most historical data, 1900-1940 and 1960-1980, to examine the extent of changes in the bumble bee fauna of Illinois. Our work provides important insights on the nature and extent of bumble bee pollinator decline in North America.