1. Customs and Border Protection Priority 1
CBP is department of the US government reporting to the Department of Homeland Security that manages the secure flow of legitimate goods and travel across our borders. Customs revenue regulations i.e. Duties, are issued under the authority of the Departments of Treasury and Homeland Security.
CBP's originally just Customs, had the responsibility of taxing imports. That role has expanded throughout our history to include a range of monitoring and security programs. CBP supports the interests of many government agencies at the point of entry and exit of goods and people. The term "Border" in this sense includes ports of entry - land, sea and air. 
Revenue - The Primal Tax
CBP administers the collection of taxes or duties on imported product. When the US was founded these duties were the only form of revenue for the federal government.
Controlling Interests
CBP's primary responsibilities include security as part of the Department of Homeland Security (DHS) and the collection of duties for the Department of Treasury. 
CBP also supports many other government agencies such as FDA, Department of Commerce, and Animal and Plant Health Inspection Service (APHIS). This last agency is responsible for monitoring wood products under the Lacey Act.
Time, Technology & Expectations
Until recently the documentation of imports and the collection of duties were managed via paperwork. Advances in communication and computer technologies now makes Customs transactions faster and more accurate. Along with this there is a greater expectation by CBP that the transactions will be more timely and more accurate.