Madison helped arrange the 1785 Mount Vernon Conference, which settled disputes regarding navigation rights on the Potomac River and also served as a model for future interstate conferences. At the 1786 Annapolis Convention, he joined with Alexander Hamilton and other delegates in calling of another convention to consider amending the Articles. After winning election to another term in Congress, Madison helped convince the other Congressmen to authorize the Philadelphia Convention to propose amendments. Though many members of Congress were wary of the changes the convention might bring, nearly all agreed that the existing government needed some sort of reform. Madison ensured that George Washington, who was popular throughout the country, and Robert Morris, who was influential in the critical state of Pennsylvania, would both broadly support Madison's plan to implement a new constitution. The outbreak of Shays' Rebellion in 1786 reinforced the necessity for constitutional reform in the eyes of Washington and other American leaders.