"how come the wheel was not in use when later Europeans arrived?"
For a wheel to be useful, you need to pair animals with it (to draw a cart, etc.) Otherwise the wheel itself is not much of a help. But there were no horses or other large draft animals in N. America until after the Spanish arrived. (Reindeer??)
Thanks. There's a reason why I love to throw questions (at the risk of showing my ignorance) out on FR--I get great answers and I learn a lot! Many thanks!