Department of Homeland Security 'U.S. Customs and Border Protection' Budget Overview (Fiscal Year 2019 Congressional Justification) [open pdf - 8MB]
From the Document: "U.S. Customs and Border Protection (CBP) is responsible for securing America's borders to protect the United States against terrorist threats and prevent the illegal entry of inadmissible persons and contraband, while facilitating lawful travel, trade, and immigration. Along over 5,000 miles of border with Canada; 1,900 miles of border with Mexico; and approximately 95,000 miles of shoreline, CBP is responsible for preventing the illegal movement of people and contraband. The FY 2019 President's Budget provides $16.7B in total budget authority to support CBP's mission. This represents an increase of $362.9M over the FY 2018 President's Budget."
U.S. Department of Homeland Security: https://www.dhs.gov/