It would drive a person crazy to dope out really what does divide the two parties. Prosperity don't divide the two parties, for under either administration the poor get poorer and the rich get richer.
Will Rogers, Bryan B. Sterling, Frances N. Sterling (1993). “Will Rogers' World: America's Foremost Political Humorist Comments on the Twenties and Thirties--and Eighties and Nineties”, p.159, Rowman & Littlefield