Interdependencies among infrastructure systems are now becoming commonplace, and present both opportunities and vulnerabilities. Initial attention was paid to functional interdependencies among infrastructure systems regardless of locational characteristics. Using electric power as a focal point, geographic interdependencies are evaluated, that is, outages that spread across several states rather than being confined to single states. The analysis evaluates the extent to which the two different groups have distinct characteristics. The characteristics examined include incident counts, number of customers lost, duration and energy unserved. Data are drawn from the Disturbance Analysis Working Group (DAWG) database, which is maintained by the North American Electric Reliability Council (NERC), and from the U.S. Energy Information Administration (EIA).