"Had some native genius invented the wheel in North America, the Euros would have found the conquest far more difficult to accomplish."
American Indians did not develop urban centers which require overland roads, infra structures and city streets. There was no need for Indians to "invent the wheel" when the Travois suited their austere lifestyle. Indians developed foot paths to seasonal quarters and to hunting regions. It is interesting to compare Aztec and Mayan highly centralized, sophisticated city-societies and ruling structures with the Egyptian Dynastic society. North American Indians for the most part evolved into small, self-subsisting communal, independent tribal and clan societies each governed by a council of wise elders. This structure contrasts with the inherited order of mythic-god rulers and ruling elites of the highly centralized So. & Cent. Americas' Indian societies which imposed tribute and taxes to support elite governance.
One could say that tribal and clan structures emulated little free republics.
The Aztecs extended their influence far to the North.