The State of California has made great strides in reducing greenhouse gas (GHG) emissions through mandated, rate-payer funded Investor Owned Utility (IOU) electricity Demand Side Management (DSM) programs. This study quantifies the amount of reduced GHG emissions in Arizona that result from DSM in that state, as well as the DSM reductions within Southern California Edison (SCE), Pacific Gas and Electric (PG&E;), and San Diego Gas and Electric (SDG&E;) during the 2010 through 2012 California Public Utilities Commission (CPUC) DSM program cycle. To accomplish this quantification, it develops a model to allocated GHG emissions based on "operating margin" resources requirements specific to each utility in order to effectively track, monitor, and quantify avoided emissions from grid-based utility resources. The developed model estimates that during the 2010-2012 program cycle, 5,327.12 metric tons (MT) of carbon dioxide equivalents (CO2e) in GHG reductions (or 1.8 percent of total reductions) can be attributed to reduced demand from Arizona--based resources by California IOUs. By focusing on the spatial context of GHG emission reductions, this study models and quantifies the spill-over effect of California's regulatory environment into neighboring states.