This map layer portrays the current routes used for conducting Breeding Bird Surveys in the lower 48 States, clipped to the HUC5/ecoregion boundary for the Sonoran Desert ecoregion. The digital data sets are used to create electronic and hard copy maps of the Breeding Bird Survey routes. The data can be used to conduct geographic analysis on national and large regional scales. The data should be displayed and analyzed at scales appropriate for 1:100,000-scale data. No responsibility is assumed by the National Atlas of the United States or by USGS Patuxent Wildlife Research Center in the use of these data.