By, what us it now, 15 states?
Article I, Section 10, Part 3:
No State shall, without the Consent of Congress, lay any Duty of Tonnage, keep Troops, or Ships of War in time of Peace, enter into any Agreement or Compact with another State or with a foreign Power...
Article I, Section 10, Part 3:
No State shall, without the Consent of Congress, lay any Duty of Tonnage, keep Troops, or Ships of War in time of Peace, enter into any Agreement or Compact with another State or with a foreign Power...