Federalism refers to the constitutional and political structure of the United States of America, according to which political power is divided among multiple levels of government: the national level of government (also referred to as the “federal” or “general” government) and that of the states. It is a multilayered system of government that reserves some powers to component entities while also establishing an overarching level of government with a specified domain of authority. The structures of federalism are set forth in the Constitution of the United States, although some related ideas and practices predated the founding period and others have developed since. The balance between federal and state power has shifted throughout U.S. history, with assertions of broad national power meeting challenges from supporters of states’ rights and state sovereignty. Federalism is a fundamental value of the American political system, and it has been a controversial political and legal question since the founding period.