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The speaker is not specific about where exactly he has been in the Northwest. We understand that he has been "over there".
Here are some more examples expressing approximate location:
The way the preposition por is used in this context is very similar to the way we use the preposition en to say "in/on" a place, although when using por there is a stronger nuance of meaning "approximate place" or "around somewhere".
Have a look at these examples where por and en are pretty much interchangable:
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