From Wikipedia:
Leon Ray Livingston (1872–1944) was a famous hobo, travelling under the name "A-No.1". He perfected the hobo symbols system, which lets other homeless people know where there are more or less generous people, free food, vicious dogs, etc. He was not a poor man; he simply preferred a life of travelling the country by train to sitting at home. He has been lauded by many American historians as the King of the Hoboes, and has followings all over the USA.
Livingston wrote several books on travelling the hobo way, including Life and Adventures of A-No.1, America's Most Celebrated Tramp. He brought attention not only to the state of the homeless in America, but also to the excitement and benefits of travelling the country for amusement. He lived and published his books in Erie, PA, and Cambridge Springs, PA.
During his later life, he continued to roam the country, but spoke out against youngsters following him. "I began out of necessity, continued because I loved the life, and now because I know nothing else." He died in 1944 and, while having a grave marked "A-No.1 At rest at last" in a Cambridge Springs, Pennsylvania cemetery, his actual body was buried in Laurel Hill Cemetery outside of Erie, Pennsylvania (source).
His book From Coast to Coast with Jack London (ISBN 99903-46-63-1) became the basis for the movie Emperor of the North (1973), directed by Robert Aldrich.