Because when they learn the origin of each of the 13 colonies in grade school that's the way Massachusetts and New England (which get a lot more time than some

Because when they learn the origin of each of the 13 colonies in grade school that's the way Massachusetts and New England (which get a lot more time than some of the other because they were one of the first and US democracy traces its roots do the Pilgrims) get taught because it's the easy way. There is a kernel of truth to it. The Pilgrims did kinda luck into settling an area that was somewhat depopulated from recent disease (but they also picked just about the most shitty area in the region so it wasn't exactly densely populated to begin with). But that line of causation gets over-played because nobody wants to stand in front of a bunch of teenagers and split hairs between various flavors of christian extremists and the circumstances by which they came to "own" the land they settled.