America has never been a melting pot - more like a salad palette, with clear boundaries between constituent parts. Melting pot is but a nice-sounding rhetoric. Racial bias aside, people usually prefer to live closer to their own kind. For minorities, this is usually because of better access to their ethnic groceries and cultural engagements.
I do not disagree with general idea in your post - I would just change the first sentence to "The salad palette is what makes America strong."