Every FDIC-insured bank branch in Williamson County, Illinois as of June 30, 2025. County land area: 420 square miles, 10.0 branches per 100 sq mi.
| Institution | Branches | Deposits |
|---|---|---|
| First Southern Bank | 9 | $322.8M |
| Banterra Bank | 9 | $561.5M |
| The Bank of Herrin | 5 | $324.7M |
| Farmers State Bank of Alto Pass, Ill. | 3 | $136.3M |
| Peoples National Bank , N.A. | 3 | $120.2M |
| Murphy-Wall State Bank and Trust Company | 2 | $3.3M |
| Legence Bank | 2 | $70.1M |
| Southern Illinois Bank | 2 | $30.7M |
| First Mid Bank & Trust, National Association | 2 | $66.6M |
| Regions Bank | 1 | $66.8M |
| Woodforest National Bank | 1 | $5.4M |
| SouthernTrust Bank | 1 | $70.0M |
| U.S. Bank National Association | 1 | $106.9M |
| Fifth Third Bank, National Association | 1 | $72.1M |