Final numbers for 2021 USL League One attendance as the season ends, led by good crowds for North Carolina FC and FC Tucson matches.
These 2021 USL League One attendance numbers are not complete. We have based this ranking on numbers officially posted to the USL League One website. Several teams have not released attendance for any games, not every match had attendance numbers posted, and some teams, such as Forward Madison, began the season playing under capacity limits. The total attendance for USL League One this season is higher than our total, but the per-game average is likely lower.
| Team | Av. | Totals | Gms | 2019 | YOY | W29 | |
| 1 | Union Omaha | 3,177 | 44,478 | 14 | NA | NA | |
| 2 | Forward Madison FC | 2,747 | 32,967 | 12 | 4,292 | -0.36 | 2,273 |
| 3 | Greenville Triumph SC | 2,384 | 33,373 | 14 | 2,509 | -0.05 | |
| 4 | Richmond Kickers | 2,078 | 29,094 | 14 | 3,468 | -0.40 | |
| 5 | Chattanooga Red Wolves | 1,822 | 25,512 | 14 | 1,632 | 0.12 | |
| 6 | North Carolina FC | 1,741 | 19,149 | 11 | 4,118 | -0.58 | 4,084 |
| 7 | S. Georgia Tormenta FC | 1,205 | 16,869 | 14 | 1,724 | -0.30 | |
| 8 | FC Tucson | 1,007 | 12,084 | 12 | 961 | 0.05 | 1,566 |
| 9 | North Texas SC | 856 | 11,125 | 13 | 1,367 | -0.37 | 821 |
| 10 | NE Revolution II | 124 | 1,365 | 11 | NA | NA | |
| 11 | Fort Lauderdale CF | 0 | 0 | 0 | NA | NA | |
| 11 | Toronto FC II | 0 | 0 | 0 | 168 | NA | NA |
| TOTALS | 1,752 | 226,016 | 129 | 1,911 | -0.08 | 8,744 | |
| WEEKLY AV. | 2,186 |
Photo courtesy Forward Madison.