what was the main purpose of both NAFTA and the USMCA that replaced it?

1. to pledge to defend each other
2. to settle border disputes among the tree countries
3. to remove trade bariorrs amoung the three counties
4. to ease border crossings between the counties

3. to remove trade barriers among the three countries

The main purpose of both NAFTA (North American Free Trade Agreement) and the USMCA (United States-Mexico-Canada Agreement) that replaced it was to remove trade barriers among the three countries.