Answer:
The oil crisis of 1971 added to severe U.S. economic problems
Advances in technology, new industries, growth of cities and new forms of transportation.
The Homestead Act was attractive to settlers, because it gave land to anyone over 21, or head of family (even women and former slaves), who applied for land, this land for a very cheap price (or no price at all) and through this it enabled easy settlement. The farmers had to then cultivate the land for a period of time, and if they did not abandon it and tended to it properly, it became their property.
Mycenaean Civilization was at its height from 1400 bc to 1200 bc.