"Just Plain Luck" what events, occurrences, or factors weren’t caused by anything or anyone, particularly, but just proved to be very fortunate for the U. S.?

Good leadership

Explanation:

In the United State today, Democracy is the form of Government and the right set up people who will ensure the sustainability of the system have always been in place. There can never be any form of coup to oust the leadership as a result of misdeed from the leadership as there is an established rule which the leaders see as a guideline for their actions. This can be regarded as pure luck for the state as many countries including many of the developed nations do not have this.

would not cooperate with each other voluntarily.