Watson is the author of books including:
- The Presidents' Wives: Reassessing the Office of the First Lady (Lynne Rienner Publishers, 2000; 2nd ed., 2014)[5]
- First Ladies of the United States: A Biographical Dictionary (Lynne Rienner Publishers, 2001)
- Affairs of State: The Untold History of Presidential Love, Sex, and Scandal (Rowman & Littlefield, 2012)[6]
- America's First Crisis: The War of 1812 (SUNY Press, 2014)[7]
- The Nazi Titanic: The Incredible Untold Story of a Doomed Ship in World War II (Da Capo Press, 2016)[8]
- The Ghost Ship of Brooklyn: An Untold Story of the American Revolution (Da Capo Press, 2017)[9]
- George Washington's Final Battle: The Epic Struggle to Build a Capital and Nation (Georgetown University Press, 2021)[10]
- Escape! The Story of the Confederacy's Infamous Libby Prison and the Civil War's Largest Jail Break (Rowman & Littlefield, 2021)
- America's First Plague: The Deadly 1793 Epidemic that Crippled a Young Nation (Rowman & Littlefield, 2023)[11]
- When Washington Burned: The British Invasion of the Capital and a Nation's Rise from the Ashes (Georgetown University Press, 2023)
His edited volumes include:
- American First Ladies (edited, Salem, 2002)[12]
- The Presidential Companion: Readings on the First Ladies (edited with Anthony J. Eksterowicz, University of South Carolina Press, 2003)[13]
- Anticipating Madam President (edited with Ann Gordon, Lynne Rienner Publishers, 2003)[14]
- America's War on Terror (edited with Patrick Hayden and Tom Lansford, Ashgate, 2003; 2nd ed., 2009)[15]
- Counting Votes: Lessons from the 2000 Presidential Election in Florida (edited, University Press of Florida, 2004)[16]
- George McGovern: A Political Life, a Political Legacy (edited, South Dakota State Historical Society Press, 2004)[17]
- Debating The War On Terrorism (edited with Tom Langsford, Kendall/Hunt, 2005)[18]
- Lincoln's Enduring Legacy: Perspectives from Great Thinkers, Great Leaders, and the American Experiment (edited with William D. Pederson and Frank J. Williams, Lexington Books, 2010)[19]