Buffalo Gap National Grassland is a National Grassland located primarily in southwestern South Dakota, United States. It is also the second largest National Grassland, after Little Missouri National Grassland in North Dakota. Characteristics of the grasslands include mixed prairie and chalky badlands. The grassland is managed by the U.S. Forest Service and is a division of Nebraska National Forest. In descending order of land area it is located in parts of Fall River, Pennington, Jackson, and Custer counties.