This topical report is a compilation of characterizations by different disciplines of the Ordovician-age Red River Formation and the oil reservoirs which it contains in an area in the southwest portion of the Williston Basin which straddles the state line between North Dakota and South Dakota. This area is off the flank from the Cedar Creek anticline, a major feature in the Williston Basin. Oil production was established in the 1950's following exploration activity on the Cedar Creek anticline. Many of the reservoirs were found by exploration aided with 2D seismic and are characterized by relatively small structures. Although there are four major porosity intervals in the Red River, only two have produced significant oil reserves.