Variations of federalism in U.S. history

Discuss the variations of federalism in U.S. history. Explain why these variations were necessary and what accomplishments occurred during these variations.

Your essay should be at least 500 words in length and include an introduction, a body, and a conclusion. You are required to use at least your textbook as source material for your response. You must also use one outside source. All sources used, including the textbook, must be referenced; paraphrased and quoted material must have accompanying citations.