The modern Hebrew term for the USA translates as “lands of the covenant.” (Artzot ha-brit.) I think that sums the constitution concept up well.
Being a single country ensures a degree of comity between states. You do not have to ask California’s permission to visit it or even move there from Illinois, or Maryland’s permission to do so from Oregon. One postal service covers the entire set of states, and the same currency is earned and spent in all. You do not have to register copyrights in fifty different places. Etc., etc.
So much for comity. Same me, same pistol, same hip.
Copyright can be handled by a 3rd party, government isn't required. And if it is, agreements can be reached about a central filing point.
Currency.... I have 3 one dollar bills, a 1000 Won note, and a 50,000 Shilling note from Uganda in my wallet. I also have a couple of pieces of plastic that work anywhere in the world. I'm going to have more problems with the paper money than the plastic.
Your arguments are understood, but they do not move me.
A covenent is between States. The thing the covenent creates, is a creation of those states.
Think on that.
/johnny