The Evolution of The King

It seems fairly obvious to me that early American readers of the Psalms would interpret it as a reference to the fledging American nation/colonies.   The majority of the colonists were Christians of one stripe or another and the original colonies were still ruled by the King in England.  Given their world-view, their religion would designated them as god's chosen/anointed and as such, completely in the right when it came appropriating the land.  This seems borne out by the reference to "heathens" in the first line, as opposed to the "nations" we have in our version.

Their reasoning essentially boils down to this:  Their God created this world, thus all of it would belong them, the chosen people of that God.  It gave them a palatable religious justification for what was essentially a wide scale, long-term invasion and genocide.

It's something that we don't think about very often now, since we're so well entrenched, but when our ancestors first arrived in this land they were military invaders.   It's interesting to note that, since both sides where so deeply connected to their spirituality in everyday life, the enter process could be viewed in religious terms; an almost direct conflict between to irreconcilable religious structures.