A project named SPREE (Superior Province Rifting Earthscope Experiment) has been undertaken by Earthscope to investigate the 2000-km-long Mid-Continent Rift System in North America. SPREE uses Earthscope's broadband Flexarray seismometers in two ways. One extends the Transportable Array, now moving across the US, into Canada, where the Mid-Continent Rift System follows or cuts the edge of the Archean Superior Craton. Second uses seismometers deployed along and across the rift in the US. Records of distant earthquakes will be analyzed to provide multiscale 3-D images of the structure of the crust and mantle beneath the rift system and its surroundings. These SPREE results will contribute to the emerging discipline of comparative riftology in which data from present, successful past, and failed rifts worldwide are being combined to give an integrated view of these complex processes.