The main reason Portugal’s shape is so tidy and rectangular is:
Because it is not.
Right. Wyoming isn’t rectangular either (surveying errors, plus earth’s curvature making the southern border about 20 miles longer than the northern border). Must be true of Colorado as well–could scarcely be otherwise!
Looks like a couple people misunderstood/misinterpreted my comment about “Spain begin[ning] by taking the NW corner of the Iberian Peninsula.” Just so we are clear, that was not intended to be a factual historical answer to the questions posed in the thread. Rather, it was the supposed start of an elaborate board game (Othello) being played in the corner of southwestern Europe. No need for error messages and the like…if you’re not sure what I was actually talking about, please go back and reread my entire post 24 :).