Most dense in U.S.: California. Least dense: The Dakotas.
Most dense Canada: Toronto, Montreal. Least dense: Northwest territories
<span>An eon is a geologically around tens of millions of years. A period is a million year included in an eon which is also made up of several eras. Therefore my answer is a period due to it being a subset of an era which is a subset of an eon.</span>
