This document provides an overview of federalism in the United States. It discusses how the balance of power between the federal and state governments has shifted over time toward greater federal control. The document also analyzes some of the advantages and disadvantages of federalism, including how it can encourage policy innovation at the state level but also create challenges for deliberation at the national level. Additionally, it examines contemporary issues around federalism such as regulation, welfare, education, crime, and same-sex marriage.