Clay ranks among the most influential figures in the United States

Henry Clay Sr. is regarded by many political historians as one of the most important house speakers in American history. A Senate Committee named Clay, along with Daniel Webster, John C. Calhoun, Robert La Follette, and Robert A. Taft was one of the top five senators in American history in 1957.

Clay was named the greatest senator in US history in a survey of historians conducted in 1986, and he was named the most significant American of all time in a survey conducted in 2006. The most qualified unsuccessful major party presidential candidate in US history, according to a 1998 survey of historians, was Clay.

Along with John C. Calhoun, William Jennings Bryan, and Alexander Hamilton, political scientists Michael G. Miller and Ken Owen named Clay as one of the four most significant American politicians who never held the office of president in 2015. According to Clay's historian James Klotter, "maybe posterity should no longer call it the Jacksonian Era... and instead call it the Age of Raw Clay." Klotter notes Clay's influence on the United States throughout the last three decades of his life.

Despite not becoming the president of the United States, he is nevertheless listed as one of the major parties' worst-performing presidential candidates who qualified in the country in 2006 and one of the most significant American politicians who was elected president in 2015.