What is the main purpose of state constitutions?

The main purpose of state constitutions is to establish the structure and function of state governments. Each state constitution serves as the foundational legal document that outlines how the government of the state will operate, including the organization of its legislative, executive, and judicial branches. It sets forth the powers and responsibilities of these branches and includes provisions for local governments as well.

While state constitutions may also include declarations about citizens' rights, their primary role revolves around specifying governmental structure and processes rather than explicitly defining these rights. The outlines of federal government powers and management of international treaties are roles reserved for the federal constitution and government, thereby not falling within the purview of state constitutions. Hence, the correct answer reflects the essential function that state constitutions serve in the American political system.