Overcrowding in the emergency departments (ED) has led to an increase in the use of ambulance diversion (AD), during which a hospital formally is not accepting patients by ambulance. We use a number of tools to considers methods by which hospitals in a metro area may cooperate to reduce diversion, including contracts and pressure from outside regulators. The tools include a birth-death process, discrete event simulations, agent-based simulation model, and some game theory to examine the potential for cooperative strategies. We use data to suggest a functional form for the payoff of such games. We find that a centralized form of routing is needed, as voluntary cooperation does not appear to be robust in the presence of noise or strategic behavior, and ethical considerations also have a significant impact.