Ports of entry are surprisingly important regulatory entities at the state level, and DC doesn't have any. Don't deflect from your ignorance.

Here is a list of usual definitions of the ordinary word port: https://dictionary.cambridge.org/dictionary/english/port . If you mean some term of art which is opposed to the usual everyday meaning of the word, it's your responsibility to be explicit. Don't deflect from your poor communication.

Doing what?

I'm a former truck driver - they levy no substantive taxes, they perform at most a cursory vehicle safety function.

Like I was unaware that oversized and overweight truck permits were an important regulatory function.