His famous elephant “Jumbo” is the mascot of Tufts University.

Barnum acquired "Jumbo," a gigantic six-ton African elephant, from the Zoological Society of London in 1882. In Britain, where the animal is revered as a national treasure, the sale was contentious, but it launched "Jumbomania" in the United States. People went to Barnum's circus where they purchased Jumbo souvenirs such as hats, postcards, and memorabilia. Even the term "jumbo" as a synonym for "large" gained popularity as a result of the elephant's notoriety. Acrobatics, monstrous performances, and General Tom Thumb are still included in Barnum and Bailey Circus, which still perform acts akin to his Traveling Menagerie.

Prior to the establishment of Tufts University, he was appointed to the Board of Trustees. He has made numerous significant contributions to the young institution, including a gift of $50,000 in 1883 (equivalent to $1,454,107 in 2021) for the establishment of the museum, later known as the Barnum Museum of Natural History, and the faculty building.

When Jumbo was unintentionally run over by a freight train and killed in 1885 while doing a performance in Ontario, Jumbo's reign came to an abrupt end. Jumbo's skin was stuffed by Barnum, who later presented it to Tufts University in Massachusetts, where he served as a trustee. Students at Tufts are referred to as "Jumbos" and Jumbo the elephant serves as the school mascot. Pachyderm was a well-liked landmark on campus until it was destroyed by fire in 1975.