the third president in a row with a five-letter surname

The third president in a row with a five-letter surname is John Quincy Adams, who served as the sixth President of the United States from 1825 to 1829. Adams was the first president to have a five-letter last name, followed by his father, John Adams, and his son, William Henry Harrison. This unusual situation has led to the popular saying, "Three presidents in a row with a five-letter surname."