The North American Breeding Bird Survey (BBS) is the primary source of long-term, large-scale population data for over 400 breeding bird species. Conducted since 1966, this standardized roadside survey relies on volunteer participation. It is coordinated in Canada by Environment and Climate Change Canada's Canadian Wildlife Service, in the United States by the U.S. Geological Survey (USGS, Patuxent Wildlife Research Center), and in Mexico by the National Commission for Knowledge and Use of Biodiversity (CONABIO). One day a year, during the peak of the breeding season and for as many years as possible, skilled BBS observers run their assigned roadside route(s). Routes consist of 50 stops spaced 0.8 km apart along a 39.4-km route. Participants record the total number of individual bird species heard from any distance or seen within 0.4 km of each stop during a three-minute observation. These data are carefully analyzed on a yearly basis to provide information on bird population trends, relative abundance and species composition and richness at the local, regional and continental scale. BBS data are freely available, and are used by scientists, wildlife managers, educators, and students, as well as by the general public.