The event that was an attempt for states to resolve their differences before the Constitutional Convention was the Annapolis Convention.
Explanation
The Annapolis Convention was held in Annapolis (Maryland), on September 11-14, in 1786 and it was created to discuss, develop and remove the trade barriers that each state had established since the government had no power to regulate trade between the states.
Only twelve delagates from five states attended the convention (New York, Pennsylvania, New Jersey, Virginia and Delaware) and it failed to accomplished its purpose, but the recommendations made by the delagates were later adopted by the U.S Congress.
