The White River Formation stretches across South Dakota, into Wyoming and terminates in Colorado. This formation contains well-preserved vertebrate fossils in sedimentary rock strata, extending from the late Eocene to the early Oligocene. During this period, there was a worldwide climate change event that caused a shift from warm-moist in the Eocene to cool-arid in the Oligocene. Pollen and spores were well preserved in this strata and have been used in studies in nearby localities (Colorado and Nebraska) as a proxy for various environmental conditions. If climatic conditions were changing, then the pollen and spores should similarly have been changing to reflect new plant groups that were moving into this area and emerging as dominant flora. Vertebrate remains in the Douglas locality indicate cooling temperatures, but this climactic event has not been studied in the Douglas locality because of the lack of plant megafossils. Pollen and spore data have been used along with megafossil in the nearby Colorado locations, which provided a baseline to compare similar palynological data from the Douglas locality. Based on standard palynological procedures, over 52 taxa of pollen and spores were identified, including pine, alder, birch, asters, grasses, and several fern species. The pollen and spore data collected is indicative of an environment that was temperate with moderate rainfall. The delayed cooling in the Douglas, Wyoming locality may be attributed to microenvironmental differences due to the proximity to the ancient North Platte River. The distribution and relative abundance of key pollen taxa in Douglas suggest non-uniform cooling in this part of North America during the Eocene-Oligocene Transition (EOT) with the persistence of warmer, moist adapted plant taxa in the Douglas section of the White River Badlands.