The more Adams thought about the future of his country, the more convinced he became that it rested on education. Before any great things are accomplished, he wrote to a correspondent, a memorable change must be made in the system of education and knowledge must become so general as to raise the lower ranks of society nearer to the higher. The education of a nation instead of being confined to a few schools and universities for the instruction of the few, must become the national care and expense for the formation of the many.

In December 2012 Allegheny County Pennsylvania announced that it would rename the 16th Street Bridge in Pittsburgh in honor of McCullough. " He started it as a book about the founding fathers and back-to-back presidents John Adams and Thomas Jefferson; but dropped Jefferson to focus on Adams. In 2003 the National Endowment for the Humanities selected McCullough for the Jefferson Lecture the U.

McCullough's two Pulitzer Prize-winning books Truman and John Adams have been adapted by HBO into a TV film and a mini-series respectively. McCullough's most recent history The Greater Journey (2011) is about Americans in Paris from the 1830s to the 1900s.