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Despite the infrequent occurrence of cascading power failures, their large sizes and enormous social costs mean that they contribute substantially to the overall risk to society from power failures in the grid. Therefore it is important to accurately understand the risk associated with such events. A cascading event may be triggered by a small subset of k components failing simultaneously or in rapid succession. While most prior work, including our own work into an efficient “Random Chemistry” method for risk analysis, has assumed that components fail independently, this paper proposes a method for deriving correlated outage probabilities such that pairs of branches that are proximate in space are more likely to fail together than distant ones. Combining Random Chemistry risk analysis with this approach to correlated outage probabilities shows that overall blackout risk can greatly increase with even small amounts of correlation. Results from the 2383-bus Polish test case under various load levels illustrate the substantial impact that correlation has on blackout risk.