It was known that there was an economic boom taking place just after the second world war. It could be due to effective economic policies implemented by various governments. Such policies include the reduction of the tax rates, and economies were regulated so as to avoid excessive spending.
The cons of it was that the Louisiana purchase pushed the Indians out of their home land
Major Turning Points in American History
1763 Treaty of Paris - Ends the French and Indian War -British policy of Salutary neglect in North America ends
1776 The Declaration of Independence -America gains independence
1789 George Washington becomes the first president under the new Constitution