The Plains CO2 Reduction (PCOR) Partnership region contains vast geologic sinks that can be used to sequester carbon dioxide (CO2) in a variety of ways. As part of the PCOR Partnership Phase I activities, the CO2 sequestration capacity of several geologic sinks in the region was estimated. Thousands of oil reservoirs, three major coal fields, and two regional deep brine formations (a.k.a. saline aquifers) were evaluated using readily available characterization data. The characterization data that were available for each sink varied widely and, therefore, all of the values for CO2 storage capacity that were developed under Phase I should be considered reconnaissance-level estimates; these estimates provide an order-of-magnitude comparison of the potential storage capacities of selected geologic sinks in the region. The estimates indicate that over 240 billion tons of CO2 could be sequestered in geologic formations in the PCOR Partnership region. Major stationary sources in the PCOR Partnership region produced nearly 590 million tons of CO2 in 2000. If this rate of CO2 production were to remain constant, the region's geologic sinks could theoretically sequester all of the CO2 produced in the region for over 400 years. One of the primary functions of the PCOR Partnership is to facilitate the implementation of geologic sequestration strategies. As part of that function, identification and characterization of sinks with a value-added component was a critical goal of the PCOR Partnership. With that in mind, major emphasis was placed on evaluation of oil and coal fields in the PCOR Partnership region. The evaluation suggested that over 3.4 billion barrels of incremental oil might be recovered from oil fields in the region through the injection of CO2, with a vast majority of the oil located in the Alberta and Williston Basins.