Which constitutional principle divides power between national and state goverments?

The constitutional principle that divides power between national and state governments is known as "federalism." Federalism works on the concept of dual sovereignty, meaning that power is shared and divided between the federal, or national, government and the state governments. Each level of government has its own set of powers and responsibilities that it can exercise independently from the other.

In the United States, the Constitution outlines the powers of the federal government and, through the Tenth Amendment, reserves all powers not delegated to the federal government to the states or the people. This creates a system where both the federal government and the state governments can operate in their respective areas of authority.

Extra: Federalism is a system that allows for a balance of power, promoting a strong national government for issues that affect the entire country, such as national defense, foreign policy, and regulating interstate commerce, but at the same time giving states the flexibility to address local needs and reflect the diverse interests and cultures of their populations. It helps to ensure that government remains closer to the citizens and can be more responsive to the specific and varying needs of different communities.

Besides the United States, other countries, such as Canada, Australia, and Germany, also operate under a federal system, though each country's system may have its own unique characteristics and division of powers. The principle of federalism continues to evolve as societies change and as the balance of power is negotiated and renegotiated between federal and state entities.