Federalism is a mode of government that combines a general government with regional governments in a single political system, dividing the powers between the two.
In the United States, federalism originally referred to belief in a stronger central government. When the United States Constitution was being drafted, the Federalist Party supported a stronger central government, while “Anti-Federalists” wanted a weaker central government. This is very different from the modern usage of “federalism” in Europe and the United States. The distinction stems from the fact that “federalism” is situated in the middle of the political spectrum between a confederacy and a unitary state. The U.S. Constitution was written as a replacement for the Articles of Confederation, under which the United States was a loose confederation with a weak central government.