What does horizontal federalism encompass?

Horizontal federalism refers specifically to the interactions and relationships among different states within a federal system. This concept is crucial in understanding how states cooperate, negotiate, and create agreements with one another, such as through compacts or shared regulations. It emphasizes the idea that states, despite their individual sovereignty, must often work together to manage shared resources, address regional issues, or tackle interstate problems that require coordinated responses.

For instance, states may enter into compacts to manage water resources that span their borders or collaborate on environmental policies to address common challenges. This cooperation is essential for maintaining a functioning federation, where different states can navigate the complexities of governance while also ensuring that their relations with one another are productive and beneficial.

While relationships between federal and state governments represent vertical federalism, interactions among different countries pertain to international relations and not federalism. Moreover, coordination among local governments does not fall under horizontal federalism, as it deals with interactions at different government levels, primarily at the state and local levels.