US Customs and Border Protection Agency
"CBP is actually the largest law enforcement organization in the United States, comprised of 20,000 Border Patrol agents deployed between the ports of entry and over 20,000 CBP officers actually stationed at the various land, air, and sea ports of entry throughout our country. They are joined by an 1,000-agent force of air and marine interdiction agents, whose job it is to implement the air and maritime responsibilities of CBP. There are an additional 2,300 agricultural specialists and other professionals that bring the sum total of CBP staffing, as is reflected in the chart,2 to over 58,000 individuals."
Tomsheck, James F., "New Border War: Corruption of U.S. Officials by Drug Cartels," Hearing before the Ad Hoc Subcommittee on State, Local, and Private Sector Preparedness and Integration, of the Senate Committee on Homeland Security and Government Affairs, (Washington, DC: US Senate, May 10, 2010), p. 6.