How Would You Concider These?

I have a few stamps from the Canal Zone. (shown) And also some from Puerto Rico. Would you put them with the U.S. or some other classification.

I use the time periods the CZ and PR were and are considered within the definition of domestic US mail rates.

I would think they were also at this time officially part of the U.S. postal service. In this case it looks like they sort of followed U.S. postal code. Notice the SRC and dates on them. For the most part I would also lump Hawaii in this as well. I thought it was interesting that Hawaii and Puerto Rico used regular issue U.S. issued stamps but Canal Zone had their own postage but it seems still under the Postal Service umbrella.