Reading about the complexities of Europe has made me wonder about when American (internal) borders were less porous. Also, were the borders between the 13 colonies completely open? Or did they at least have had customs houses to collect trade tariffs?

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    The constitution forbids states from collecting an internal tariff (Interstate Commerce clause). During the Articles of Confederation, states could, and did tax commerce between states.
    – MCW
    Jul 12, 2015 at 10:59
  • @MarkC.Wallace Could you be a little more specific? As I find it anywhere, the Commerce Clause just states that the Congress has power to regulate interstatal & international commerce. But that wording (as I understand it) would allow for internal tariffs (as long as the Congress supports -or at least do not oppose- them) the same way that it allows for the Congress setting external tariffs.
    – SJuan76
    Jul 12, 2015 at 16:49
  • Gibbons established that regulation was the sole province of the Federal government. (If I had the time to do real research, I'd do enough to enter this an answer. )
    – MCW
    Jul 12, 2015 at 18:07
  • technically those all still exist. Not only are there international airports all over the continental USA, but the US border patrol ranges far inland from especially the Mexican border, setting up roadblocks and checkpoints to catch illiegal immigrants and human traficking attempts.
    – jwenting
    Aug 21, 2015 at 5:39
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    @Michael Seifert: Actually, California employs agricultural inspections as recently as today. (Well, probably: from personal experience I know they had them a week ago.)
    – jamesqf
    Dec 12, 2018 at 19:07

2 Answers 2


I can't speak to the early cases of the colonies, but today there are still border patrol stations within the United States. The one I have been through several times is the San Clemente station, 67 miles from Mexico on Interstate 5, in Marine Corps base Camp Pendleton:

The San Clemente Border Patrol Station maintains a full-time traffic checkpoint on the northbound lanes of Interstate 5. It is one of seven stations in the San Diego Border Patrol Sector and operations one of four checkpoints. Checkpoint activities are directed against the smuggling of illegal aliens and narcotics away from the border area.

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    Here is a list of all (or most) USA internal border control checkpoints - en.wikipedia.org/wiki/…
    – ed.hank
    Dec 11, 2018 at 19:26
  • Those checkpoints are not on any border though, and they are not intended to control traffic across internal borders. They are intended to serve as backup enforcement for the external border. (Also @ed.hank)
    – phoog
    Jan 22, 2020 at 5:42

Article 1, Section 8 of the Constitution states:

The Congress shall have Power To lay and collect Taxes, Duties, Imposts and Excises, to pay the Debts and provide for the common Defence and general Welfare of the United States; but all Duties, Imposts and Excises shall be uniform throughout the United States;

Article 1, Section 9 states:

No Tax or Duty shall be laid on Articles exported from any State.

The borders of the United States have been porous for most of our history, however during much of the twentieth century the immigration laws were more strictly enforced. This began to change about the mid-1960's.

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