Charles Francis Adams Jr. (1835-1915) was an American historian and author, known for his contributions to the study of American history. He was the son of Charles Francis Adams, a prominent politician and diplomat, and the grandson of John Quincy Adams, the sixth President of the United States. Adams Jr. played a significant role in preserving historical documents and was involved in various historical societies. In addition to his historical work, Adams Jr. was a successful businessman and served as the president of the Union Pacific Railroad. He wrote several books, including a notable biography of his father, and was instrumental in promoting the importance of historical research and education in America.