Where is the highest population density in the eastern united states

During which era in earth's history were the first insects? mesozoic precambrian cenozoic paleozoic

Plz answer ! find the alps. what countries and country borders intersect this major mountain range? which borders seem to be defined by the edges of the mountains? which borders seem to be defined by the edges of the mountains? which borders cut across the mountains?

Monk's mound in cahokia is an enormous earthwork very near to the mississippi river. what do archaeologists believe it was used for?