Which defines the powers held by each level of government in the US?

The powers held by each level of government in the U.S. are defined by the Constitution, which establishes a federal system. The federal government has enumerated powers, such as regulating interstate commerce and conducting foreign affairs, while state governments have reserved powers, including regulating education and local law enforcement. Additionally, some powers are concurrent, meaning they are shared by both levels, such as the ability to tax and enforce laws. This division aims to balance authority and ensure a system of checks and balances among different government levels.