| Rank | County | Percentage with High School Diploma | 
                            
                                
                                    | 1 | Lincoln County, South Dakota | 95.4% | 
                            
                                
                                    | 2 | Clay County, South Dakota | 94.6% | 
                            
                                
                                    | 3 | Hughes County, South Dakota | 93.4% | 
                            
                                
                                    | 4 | Haakon County, South Dakota | 93.0% | 
                            
                                
                                    | 5 | Lawrence County, South Dakota | 92.7% | 
                            
                                
                                    | 6 | Sully County, South Dakota | 92.7% | 
                            
                                
                                    | 7 | Custer County, South Dakota | 92.5% | 
                            
                                
                                    | 8 | Meade County, South Dakota | 92.4% | 
                            
                                
                                    | 9 | Brookings County, South Dakota | 92.4% | 
                            
                                
                                    | 10 | McCook County, South Dakota | 92.3% | 
                            
                                
                                    | 11 | Union County, South Dakota | 91.9% | 
                            
                                
                                    | 12 | Pennington County, South Dakota | 91.7% | 
                            
                                
                                    | 13 | Lake County, South Dakota | 91.7% | 
                            
                                
                                    | 14 | Brown County, South Dakota | 91.3% | 
                            
                                
                                    | 15 | Turner County, South Dakota | 90.9% | 
                            
                                
                                    | 16 | Stanley County, South Dakota | 90.9% | 
                            
                                
                                    | 17 | Minnehaha County, South Dakota | 90.8% | 
                            
                                
                                    | 18 | Codington County, South Dakota | 90.1% | 
                            
                                
                                    | 19 | Moody County, South Dakota | 90.1% | 
                            
                                
                                    | 20 | Fall River County, South Dakota | 90.0% | 
                            
                                
                                    | 21 | Jones County, South Dakota | 89.7% | 
                            
                                
                                    | 22 | Aurora County, South Dakota | 89.2% | 
                            
                                
                                    | 23 | Yankton County, South Dakota | 89.0% | 
                            
                                
                                    | 24 | Davison County, South Dakota | 88.9% | 
                            
                                
                                    | 25 | Kingsbury County, South Dakota | 88.6% | 
                            
                                
                                    | 26 | Hamlin County, South Dakota | 88.4% | 
                            
                                
                                    | 27 | Miner County, South Dakota | 88.2% | 
                            
                                
                                    | 28 | Day County, South Dakota | 88.1% | 
                            
                                
                                    | 29 | Harding County, South Dakota | 88.0% | 
                            
                                
                                    | 30 | Tripp County, South Dakota | 87.8% | 
                            
                                
                                    | 31 | Brule County, South Dakota | 87.7% | 
                            
                                
                                    | 32 | Hanson County, South Dakota | 87.5% | 
                            
                                
                                    | 33 | Perkins County, South Dakota | 87.4% | 
                            
                                
                                    | 34 | Roberts County, South Dakota | 87.3% | 
                            
                                
                                    | 35 | Sanborn County, South Dakota | 87.2% | 
                            
                                
                                    | 36 | Hand County, South Dakota | 87.1% | 
                            
                                
                                    | 37 | Potter County, South Dakota | 86.9% | 
                            
                                
                                    | 38 | Marshall County, South Dakota | 86.6% | 
                            
                                
                                    | 39 | Hyde County, South Dakota | 86.6% | 
                            
                                
                                    | 40 | Gregory County, South Dakota | 86.6% | 
                            
                                
                                    | 41 | Spink County, South Dakota | 86.5% | 
                            
                                
                                    | 42 | Butte County, South Dakota | 86.5% | 
                            
                                
                                    | 43 | Clark County, South Dakota | 86.3% | 
                            
                                
                                    | 44 | Walworth County, South Dakota | 86.3% | 
                            
                                
                                    | 45 | Lyman County, South Dakota | 86.0% | 
                            
                                
                                    | 46 | Jackson County, South Dakota | 85.9% | 
                            
                                
                                    | 47 | Faulk County, South Dakota | 85.8% | 
                            
                                
                                    | 48 | Grant County, South Dakota | 85.8% | 
                            
                                
                                    | 49 | Bon Homme County, South Dakota | 85.4% | 
                            
                                
                                    | 50 | Edmunds County, South Dakota | 85.3% | 
                            
                                
                                    | 51 | Deuel County, South Dakota | 84.5% | 
                            
                                
                                    | 52 | Corson County, South Dakota | 84.3% | 
                            
                                
                                    | 53 | Charles Mix County, South Dakota | 83.9% | 
                            
                                
                                    | 54 | Beadle County, South Dakota | 83.7% | 
                            
                                
                                    | 55 | Campbell County, South Dakota | 83.4% | 
                            
                                
                                    | 56 | Jerauld County, South Dakota | 83.4% | 
                            
                                
                                    | 57 | Mellette County, South Dakota | 82.6% | 
                            
                                
                                    | 58 | Ziebach County, South Dakota | 81.5% | 
                            
                                
                                    | 59 | Hutchinson County, South Dakota | 81.4% | 
                            
                                
                                    | 60 | Bennett County, South Dakota | 80.7% | 
                            
                                
                                    | 61 | Todd County, South Dakota | 79.7% | 
                            
                                
                                    | 62 | Buffalo County, South Dakota | 78.2% | 
                            
                                
                                    | 63 | Shannon County, South Dakota | 78.0% | 
                            
                                
                                    | 64 | Dewey County, South Dakota | 77.4% | 
                            
                                
                                    | 65 | Douglas County, South Dakota | 76.6% | 
                            
                                
                                    | 66 | McPherson County, South Dakota | 73.2% |