| | | National Park Service | +12022086843 | Mon-Fri: 9:00 AM - 5:00 PM | National parks management, conservation |
Federal Communications Commission | +18882255322 | Mon-Fri: 8:00 AM - 8:00 PM | Telecommunications regulation, spectrum management |
Internal Revenue Service | +18008291040 | Mon-Fri: 7:00 AM - 7:00 PM | Tax information, refunds, filing assistance |
Department of Energy | +12025865000 | Mon-Fri: 8:00 AM - 5:00 PM | Energy policy, nuclear safety, research |
U.S. Postal Service (USPS) | +18002758777 | Mon-Fri: 8:00 AM - 8:00 PM | Mail services, postage, package tracking |
Department of Homeland | +12022828000 | Mon-Fri: 9:00 AM - 5:00 PM | Border security, immigration, emergency response |
United States Secret Service | +12024065708 | 24/7 | Presidential protection |
National Institutes of | +13014964000 | Mon-Fri: 8:30 AM - 5:00 PM | Biomedical research, medical studies |