Why did, for the most part, America adopt an isolationist foreign policy after the revolutionary war

An isolationist policy partially protected the new vulnerable nation as well as allowing the nation to maintain a small military.

The US was physically vulnerable following the Revolutionary War and it they were to be tangled up with a European nation in an alliance that led to war then they could lose land or even their newly formed independence. The geographic location of the US made it easier to protect the new nation and support the idea of isolation from European affairs. George Washington urged in his Farewell Address to avoid alliances with foreign powers. The military could also remain small if the US had no reason to enter into war. This was supported by the Democratic-Republicans who were fearful of a powerful federal government. Keeping the military small meant that the federal government was less likely to use it against the citizens of the country.