In the 1840 presidential election, Whig candidate William Henry Harrison was attacked by Democrats on the false allegation that he had once been a supporter of John Adams.[360] Adams was eventually subject to criticism from states' rights advocates. Edward A. Pollard, a strong supporter of the Confederacy during the American Civil War, singled out Adams, writing:

The first President from the North, John Adams, asserted and essayed to put into practice the supremacy of the "National" power over the states and the citizens thereof. He was sustained in his attempted usurpations by all the New England states and by a powerful public sentiment in each of the Middle States. The "strict constructionists" of the Constitution were not slow in raising the standard of opposition against a pernicious error.[361]
In the 21st century, Adams remains less well known than many of America's other Founding Fathers, in accordance with his predictions. McCullough argued that "[t]he problem with Adams is that most Americans know nothing about him."