| Index | Johnston City | Illinois | National |
| Average Test Scores | 19% | 33% | 48% |
| Student/Teacher ratio | 20:1 | 18:1 | 16:1 |
| Total public schools | 4 | 3,938 | 79,221 |
| Total private schools | n/a | 1,438 | 24,874 |
| Total post-secondary schools | n/a | 306 | 7,963 |
| Index | Johnston City | Illinois | National |
| Completed 8th grade | 73.6% | 86.2% | 84.3% |
| Completed high school | 71.1% | 84.7% | 83.0% |
| Completed some college | 40.6% | 61.8% | 59.4% |
| Completed associate degree | 19.4% | 40.7% | 38.5% |
| Completed bachelors | 7.9% | 32.9% | 30.3% |
| Completed masters | 1.3% | 12.7% | 11.5% |
| Completed professional degree | 0.0% | 3.4% | 3.3% |
| Completed doctorate | 0.0% | 1.2% | 1.3% |
There are a total of 4 public schools, n/a private schools and n/a post-secondary schools in Johnston City. Using the proficiency score averages, the average test scores for Johnston City, IL schools is 19%. The average student to teacher ratio is 20:1. In Johnston City, IL, an average of 73.6% of students have completed 8th grade and an average of 71.1% have completed high school.
| City | Population | Avg. Test Scores | National Avg. |
| Carterville, IL | 5,861 | 53% | 10.9% |
| Creal Springs, IL | 473 | 42% | 12.5% |
| Herrin, IL | 12,806 | 36% | 24.7% |
| Marion, IL | 17,539 | 33% | 30.9% |
| Benton, IL | 6,977 | 27% | 44.4% |
| Johnston City, IL | 3,414 | 19% | 60.4% |
| City | Population | Avg. Test Scores | National Avg. |
| Hanover, MN | 3,414 | 81% | 67.7% |
| West Liberty, KY | 3,414 | 52% | 8.5% |
| Angwin, CA | 3,415 | 55% | 14.6% |
| New Hampton, IA | 3,413 | 77% | 60.1% |
| Maiden, NC | 3,413 | 43% | 10.2% |
| Johnston City, IL | 3,414 | 19% | 60.4% |
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