If you want to make an argument about what a port is, picking land "points of entry" isn't a good argument.

Airports are a better yardstick.

A new Capitol State could easily establish both a port and points of entry if it so chose, the Potomac is somewhat in practice (and legally) a navigable river and there are US highways and interstates that go thru Washington DC.

Furthermore the WMAA would likely come under the control of the city.

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.