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?

1 Answer 1


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, 2021 at 21:58
  • 4
    Yes, CBP has jurisdiction AT the airport, but not everywhere within 100 miles of the airport. Apr 12, 2021 at 22:01
  • 2
    As the ACLU document indicates "cannot" is in reality "should not." (True of almost every law enforcement agency.)
    – WGroleau
    Apr 12, 2021 at 22:04
  • Thanks. This is a really great answer.
    – Patrick
    Apr 13, 2021 at 7:44
  • I wouldn't put it past Border Patrol to argue that the 100-mile zone should include the areas around airports, since airports are for some purposes formally "the functional equivalent of" the external border. Some judges would surely rule in favor of such a claim. But I don't think they've yet actually tried to advance the claim. It should also be noted that the 100-mile zone only applies to certain limited powers of immigration officers. Their other powers apply everywhere, so they can act on "reasonable suspicion" and "probable cause" anywhere in the US.
    – phoog
    Feb 16 at 18:29

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