|Appeared in:|| And to Think That I Saw It on Mulberry Street |
Marco was named after Marco McClintock, the son of the author's editor, Marshall "Mike" McClintock, and Helene McClintock, to whom the book is dedicated. Marco returned as a character in McElligot's Pool.
- In McElligot's Pool, he is shown trying to catch fish in a pond of the same name as the book, while in ATTTISIOMBS, he just walks home from school.
- On the movie In Search of Dr. Seuss He is a character in direct to video film, but is portrayed by two different Actors. J. D. Daniels from Mulberry Street, and Brady Bluhm in McElliigot's Pool.