George P. A. Healy; "I knew no one in France, I was utterly ignorant of the language, I did not know what I should do when once there; but I was not yet one-and-twenty, and I had a great stock of courage, of inexperience—which is sometimes a great help—and a strong desire to be my very best.

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.