| Abbreviation | Definition |
|---|---|
| GTAA | Greater Toronto Airports Authority |
| GTTA | Greater Toronto Transit Authority |
| GWTA | Goldsboro Wayne Transportation Authority |
| HA | Hospital Authority |
| HAA | Highway Authority Agreements |
| HACA | Housing Authority City Of Austin |
| HACE | Housing Authority of the City of Elizabeth |
| HACPP | Housing Authority of the City of Point Pleasant |
| HACV | Housing Authority of the City of Vallejo |
| HADA | Hyderabad Airport Development Authority |
| HAFTA | Holding Authority Figures To Account |
| HAIG | Housing Authority Insurance Group |
| HART | Honolulu Authority for Rapid Transportation |
| HASB | Housing Authority of South Bend |
| HASLO | Housing Authority of San Luis Obispo |
| HASP | Headwater Authority of the South Platte |
| HATC | High Authority for Tender Control |
| HCA | Hazleton City Authority |
| HCAA | Hellenic Civil Aviation Authority |
| HCHA | Harris County Housing Authority |