The primary reason why the 2010 Affordable Care Act stands as one of the most important domestic policy plans in recent history is because it was the first of its kind. Universal healthcare had never existed in the United States before.
History is a subject that describe about the past
The economy in the United States in the 1920's varied greatly from European countries. After WWl, Europe struggled to rebuild. Europe had taken the brunt of the attacks and went into a deep depression. The United States in contrast boomed. The economy was better than ever before. Since no attacks had happened on American soil, we were able to mass produce consumer goods, etc. People were buying on credit, investing in the stock market, and moving to the city. Life was good in America; not so good in Europe.
The correct answer is manifest destiny.
Manifest destiny is the belief that it was America's god given right to expand from "sea to shining sea." In other words, it was America's destiny to expand their control across the entire North American continent from the Atlantic to the Pacific Ocean. This belief resulted in the US buying land from other countries, fighting in wars, and taking land from Native Americans in order to achieve this goal. This was present throughout American society during the early to middle of the 19th century.