Of the 36 diurnal raptor species in North America, 31 (~86%) are either complete or partial migrants. During fall and spring, raptors use "leading lines" or topographic features, such as mountain ranges, rivers, and coastlines that help guide them during their migration, and sometimes are redirected by diversion lines, or barriers that they are hesitant to cross (e.g., large bodies of water). Our objective was to assess the use of mountain ranges and rivers in central and southeastern Arizona by migrating raptors and to determine physical and ecological factors that are important to raptor migration across the United States. We counted migrating raptors in the spring and fall for two years at ten paired count stations in central and southeastern Arizona. Arizona counts were incorporated with counts from across the United States to determine physical and ecological features that influence migration rates. Raptor counts for central and southeastern Arizona averaged 2.0 raptors/hour, and were similar to what is observed at most other counting stations in the Central and Pacific Flyways. Stepwise regression models for the United States indicated counts were negatively related to distance from a diversion barrier and positively related to continuity of elevation. Understanding the factors that influence migrating raptors will inform decisions about environmental modifications and their potential influence on raptor populations. The following appendices are written and formatted to be submitted to journals. Although part of a thesis, they are written in plural to reflect the necessary authorship for journal submission. The first appendix, titled "Assessment of raptor migration corridors in central and southeastern Arizona", will be submitted to the Southwestern Naturalist. The second appendix, title "Assessment of raptor migration corridors in the United States", will be submitted to the Journal of Raptor Research.