Causes:

Taxes imposed by Britain upon American colonialists was the primary cause of the American Revolutionary War.

Effects:

The Boston Tea Party humiliated the English monarchy that then imposed punitive laws on Massachusetts in 1774 known as the Coercive Acts, following which Patriots in the other colonies rallied behind Massachusetts.  In late 1775, the Patriots in each of the thirteen colonies formed Provincial Congresses set up their own alternative government to better coordinate their resistance efforts against Great Britain. Other colonists, known as Loyalists, preferred to remain aligned to the British Crown.