U.S. Customs and Border Protection: 
https://www.cbp.gov

Homeland Security:
https://www.dhs.gov

U.S. FOOD & DRUG:
https://www.fda.gov

Transportation Security Administration:
https://www.tsa.gov

United States Environmental Protection Agency:
https://www.epa.gov

Department of Transportation:
https://www.transportation.gov

U.S. Energy Information Administration
https://www.eia.gov