I vaguely remember hearing somewhere that U.S. Customs and Border Patrol has a jurisdictional definition that allows them to be active a certain number of miles from international ports of entry, and that this jurisdictional definition allows them to act within most major cities, since large airports are considered ports of entry.

Can someone give me a link that explains the exact radius in miles within which CBP can act?


Federal regulations allow the US Customs and Border Patrol to operate "anywhere within 100 miles of any US external boundary". "External boundary" includes the Canadian and Mexican borders, sea coasts and the great lakes; but it does not include airports.

The zone does include many major cities, not because airports count but because many major cities are within 100 miles of of an external boundary. About two thirds of the US population lives within the zone.

The CBP does not have the same powers in the zone that they have at the border. They cannot stop or search someone away from the border without reasonable suspicion or probable cause.

Here is an ACLU page explaining what the powers and restrictions on the CBP are within this zone., and includes a map.

  • It’s possible to fly non-stop from outside USA to Denver. Surely customs, though not border patrol, is functioning there? – WGroleau Apr 12 at 21:58
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    Yes, CBP has jurisdiction AT the airport, but not everywhere within 100 miles of the airport. – DJClayworth Apr 12 at 22:01
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    As the ACLU document indicates "cannot" is in reality "should not." (True of almost every law enforcement agency.) – WGroleau Apr 12 at 22:04
  • Thanks. This is a really great answer. – Patrick Apr 13 at 7:44

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