How did the spirit of "manifest destiny" gave a new stridency to ideas of racial superiority?

Question

How did the spirit of "manifest destiny" gave a new stridency to ideas of racial superiority?

Answer 1

It was their excuse to take anything they wanted no matter how many hundreds of thousands they killed to do it

It made them worse than the n***s in europe ever dared to be

Answer 2

Manifest Destiny was the belief that America was "predestined" to expand its territory from the Atlantic to the Pacific.  This predestination allowed us to systemically remove the occupants of said lands without regard for their rights.  These occupants being predominantly Mexicans and Native Americans, although there were many other groups occupying these territories.  

I guess the fact that Americans believed they were destined by God to control the land would be the glaring example of racial superiority, but it became the excuse for atrocities committed against other races up until the 1950's (I think) when we acquired Hawaii.  Some could say it happens today with military testing of napalm in Vieques, Puerto Rico.  That would be my answer.