For nearly 20 yr, the Midwest Regional Carbon Sequestration Partnership (MRCSP), under the direction of Battelle Memorial Institute, has collected geologic data from a 10-state region to assess the potential for carbon dioxide (CO2) storage. The Partnership region is geographically diverse, encompassing nine physiographic provinces, two major depositional basins (Appalachian and Michigan), and extending offshore to the Outer Continental Shelf. This large region holds much potential for carbon storage and utilization, but understanding the complexities of the subsurface geological framework commonly presents an entry barrier for potential stakeholders. To help address this technical issue, geoscientists from across the Partnership region contributed digital data sets related to oil and gas reservoirs, with emphasis on legacy oil fields that hold potential for enhanced oil recovery using CO2. The result is the MRCSP petroleum fields database. To date, this extensive compilation contains spatial data on the reservoir characteristics of more than 4000 petroleum fields. Multiple resources were used for data collection, quality control, and geospatial updates to fields data across the region. These resources included existing databases, such as the Tertiary Oil Recovery Information System, historical oil and gas records, previously published information, and statistical analyses. This work will enable stakeholders from various backgrounds to evaluate CO2 storage opportunities on a regional and/or field-specific basis.