Positive:
The years following the end of WW2 saw the United States consolidating as a superpower and the emergence of a global actor only equaled by the Soviet Union at the time. Efforts to prevent further conflicts in global scale resulted in the creation of the United Nations. The headquarters of many other multilateral organizations was lead by the US foreign policy that formerly didn't play such an active role
The "Marshal Plan" became a key for reconstruction of the European economies and it saw an emergence of financial institutions that fostered cooperation and development to many countries. This includes the World Bank, International Monetary Fund. This multilateral organisms were key to reconstruction of countries damaged by war.
Negative:
The policy of containment, and later the Cold war generated local conflicts, where famous cases like Vietnam generated a bad image to the World where Us should have not been involved
to prevent the spread of communism, saw the formation of the NATO, that nowadays is seen as an intromission from the US into European politics especially in the sphere of military and defense. Nato generates a huge military budget and relies on American troops when Europeans could be more involved in solving their particular issues and being more autonomous
Electricity can change the life of the average American by providing lighting, ways to keep food from spoiling, along with ways of cooking the food in more efficient ways that would not have been possible before without electricity.
The Louisiana Purchase was a negotiation between France and The U.S. in 1803 where the U.S. paid $15 million for approximately 827,000 squared miles
Geography played a critical role in the economic development of New York, Boston, and Charleston, since all of these cities were located on the Atlantic Ocean and had protected harbors, that allowed for unprecedented levels of trade with both other states and other nations.
