| 1848 | Washington Gas Light Company received charter from Congress |
| 1917 | Washington Gas purchased Rosslyn Gas Company in Virginia and added it to
controlling interest already held in Georgetown Gaslight Company |
| 1939 | Alexandria Gas Company, founded in 1851, acquired by Washington Gas |
| 1959 | Washington Gas acquired Shenandoah Gas Company |
| 1963 | WGL announced that a new subsidiary, Hampshire Gas Company, planned to
acquire and operate a natural gas field in West Virginia |
| 1964 | Stock of Frederick Gas Company (MD) acquired by Washington Gas |
| 1996 | Frederick Gas Company merged into parent Washington Gas |
| 1998 | Washington Gas sold West Virginia distribution assets to Mountaineer Gas |
| 2000 | Shenandoah Gas Company merged into parent Washington Gas |
| 2000 | WGL Holdings, Inc. established and became the parent holding company for
Washington Gas Light Company and each of its subsidiaries |
