Final answer:
The Emergency Management Assistance Compact (EMAC) is the provision that allows for cooperation across state lines, enabling the sharing of emergency services and equipment during large disasters.
Step-by-step explanation:
If a large disaster such as an earthquake or hurricane occurs that requires cooperation across state lines, the provision that allows for cooperation between states, enabling the sharing of EMS personnel and equipment, is known as an Emergency Management Assistance Compact (EMAC). EMAC is an interstate agreement that provides a legal framework for states to assist each other in response to all kinds of emergencies. This agreement streamlines the process through which states can share resources, thereby ensuring a more efficient and coordinated response to disasters.