The US took over former land claimed by France and Spain. Very few Spanish and French actually lived there. It was mostly territory claimed by Spain and France, but almost totally unsettled. The land was populated with Indians, but they had already seen their populations ravaged by European disease.

Somewhere like Illinois is littered with places named in French or Algonquin, but there is zero culture leftover.

Parts of Lousinana are all that's left from France.