I enjoyed your take! I would observe one glaring hole in your census of Old American European ethnic groups: the Germans. They are the largest European ethnic group ancestry today. Huge numbers came in the 1800s and they had a singular effect on the American culture that would evolve post-Appomattox. In fact, I read in the past that there were something like over 100 German language newspapers in the various Midwest cities (and the Germans settled largely in a belt from Philadelphia to Milwaukee) on the eve of World War I. Because of propaganda in that war and the big rise in anti-German sentiment that came with it, they largely faded into the background post-war, and thoroughly intermarried with all the other European ethnics to escape the effects of that cultural isolation.