| South Jersey Gas Co | Owner/operator | Atlantic City, NJ | | 1 |
| South Louisiana Ethanol, LLC | Owner/operator | | 1 | |
| South Portland Terminal LLC | Owner/operator | | | 1 |
| South Shore Pipeline Co LLC | Owner/operator | Houston, TX | | 1 |
| South Wilmington-Pipeline | Owner/operator | Wilmington, NC | | 1 |
| Southcoast Production Inc | Owner/operator | | | 2 |
| Southcross Alabama Gathering System, L.p. | Owner/operator | Dallas, TX | | 1 |
| Southcross Alabama Pipeline LLC | Owner/operator | | | |
| Southcross CCNG Gathering LTD | Owner/operator | | | |
| Southcross CCNG Transmission LTD | Owner/operator | | | |
| Southcross Energy GP LLC | Owner/operator | | | 2 |
| Southcross Gathering Ltd. | Owner/operator | Dallas, TX | | 1 |
| Southcross Gulf Coast Transmission, LTD | Owner/operator | Houston, TX | | 1 |
| Southcross Mississippi Industrial Gas Sales, L.p. | Owner/operator | Dallas, TX | | 1 |
| Southcross Mississippi Pipeline, L.p. | Owner/operator | | | |
| Southcross Mustang Transmission, Ltd. | Owner/operator | | | |
| Southcross NGL Pipeline Ltd. | Owner/operator | | | |
| Southcross Nueces Pipelines LLC | Owner/operator | Dallas, TX | | 1 |
| Southcross Processing LLC | Owner/operator | | | 1 |
| Southeast Alabama Gas District | Owner/operator | | | |
| Southeast Connections, LLC | Contractor | Conyers, GA | 3 | |
| Southeast Directional Drilling | Contractor | | 4 | |
| Southeast Emulsions Inc | Owner/operator | | | 2 |
| Southeast Gas | Owner/operator | Andalusia, AL | | 1 |
| Southeast Gas Storage, LLC | Owner/operator | | 1 | |
| Southeast Gas Transmission | Owner/operator | Crystal Springs, MS | | 1 |
| Southeast Storage Development Co, LLC | Owner/operator | | 1 | |
| Southeast Supply Header, LLC | Owner/operator | Houston, TX | 6 | 1 |
| Southeastern Kansas Pipeline & Transmission Co, LLC | Owner/operator | Fort Worth, TX | | 1 |
| Southeastern Natural Gas Co | Owner/operator | Canton, OH | | 1 |
| Southern California Gas Co | Owner/operator | Los Angeles, CA | 4 | 5 |
| Southern Company | Owner/operator | | 1 | |
| Southern Company Pipelines | Owner/operator | Birmingham, AL | | 1 |
| Southern Connecticut Gas Co | Owner/operator | Orange, CT | | |
| Southern Dome, LLC | Owner/operator | Houston, TX | | 1 |
| Southern Energy Operating LLC | Owner/operator | New Hebron, MS | | 1 |
| Southern Gas Transmission | Owner/operator | Houston, TX | | 1 |
| Southern Gulf LNG Company LLC | Owner/operator | Houston, TX | | |
| Southern Illinois Power Cooperative | Owner/operator | Marion, IL | | 1 |
| Southern Indiana Gas & Electric Co | Owner/operator | Evansville, IN | | 5 |
| Southern Industrial Gas Corp | Owner/operator | | | |
| Southern Kentucky Energy, LLC | Owner/operator | Caneyville, KY | | 1 |
| Southern Lng, Inc | Owner/operator | Houston, TX | 4 | 1 |
| Southern Missouri Gas Company, L.p. | Owner/operator | Tulsa, MO | | 1 |
| Southern Natural Gas Co., LLC & Elba Express Co., LLC | Owner/operator | | 1 | |
| Southern Natural Gas Company, L.L.C. | Owner/operator | Houston, TX | 51 | 2 |
| Southern Naturalgas Company | Owner/operator | | 1 | |
| Southern Oil Of Louisiana LLC | Owner/operator | | 3 | |
| Southern Star CTL Gas Pipeline Inc | Owner/operator | | | 5 |
| Southern Star Central Gas Pipeline, Inc. | Owner/operator | Owensboro, KY | 50 | 9 |