| Index | Custer | South Dakota | National |
| Average Test Scores | 50% | 48% | 48% |
| Student/Teacher ratio | 12:1 | 14:1 | 16:1 |
| Total public schools | 6 | 340 | 79,221 |
| Total private schools | n/a | 76 | 24,874 |
| Total post-secondary schools | n/a | 25 | 7,963 |
| Index | Custer | South Dakota | National |
| Completed 8th grade | 89.6% | 89.1% | 84.3% |
| Completed high school | 86.1% | 86.8% | 83.0% |
| Completed some college | 59.5% | 60.4% | 59.4% |
| Completed associate degree | 33.6% | 38.5% | 38.5% |
| Completed bachelors | 22.9% | 27.5% | 30.3% |
| Completed masters | 4.2% | 8.1% | 11.5% |
| Completed professional degree | 0.9% | 2.5% | 3.3% |
| Completed doctorate | 0.8% | 1.2% | 1.3% |
There are a total of 6 public schools, n/a private schools and n/a post-secondary schools in Custer. Using the proficiency score averages, the average test scores for Custer, SD schools is 50%. The average student to teacher ratio is 12:1. In Custer, SD, an average of 89.6% of students have completed 8th grade and an average of 86.1% have completed high school.
| City | Population | Avg. Test Scores | National Avg. |
| Hill City, SD | 587 | 62% | 29.5% |
| Custer, SD | 2,314 | 50% | 3.1% |
| City | Population | Avg. Test Scores | National Avg. |
| Petersburg, IN | 2,315 | 38% | 20.1% |
| Brownsville, PA | 2,313 | 34% | 29.5% |
| Collinsville, AL | 2,312 | 25% | 49.0% |
| Zwolle, LA | 2,312 | 68% | 40.6% |
| Chiefland, FL | 2,312 | 51% | 5.7% |
| Custer, SD | 2,314 | 50% | 3.1% |
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