What is a state compact?

A state compact is a formal agreement between two or more states that, in most cases, requires approval by Congress. This requirement is established under the U.S. Constitution, which specifies that states cannot enter into agreements or compacts with each other without such approval, thus ensuring that these agreements do not conflict with federal law or policy.

Compacts can cover a wide range of topics including resource management, transportation, or shared services and aim to facilitate cooperation and address regional challenges. The necessity for Congressional approval adds a layer of federal oversight, ensuring that state interests align with national interests and legal frameworks. This mechanism fosters collaborative governance among states while reinforcing the federal system's structure.

While the other options may suggest different forms of agreements or governance structures, they do not capture the specific legal requirement for Congressional approval nor the formal nature of state compacts. Options like treaties and rules passed by Congress pertain to different legal contexts and processes within federalism.