Old Idaho Penitentiary Celebrates ‘Dennis the Cat Day’

The Old Idaho Penitentiary will host its annual Dennis the Cat Day to celebrate “one of the site’s best liked and most respected figures” from 12-5 p.m. Sunday at 2445 Old Penitentiary Road in Boise.

According to an Idaho State Historical Society press release, there will be food trucks, local vendors, limited edition Dennis the Cat Day merchandise available for purchase and presentations during the festivities.

Legend has it that Dennis the Cat was smuggled into the prison as a kitten by an inmate. He lived at the penitentiary for 16 years and was well loved by inmates and staff alike. 

Upon his death in 1968, the inmates at the Old Idaho Penitentiary created a headstone for the beloved cat. It is the only marked grave within the prison. Since then, Dennis the Cat has become a mascot for the penitentiary, with members of the public continuing to pay their respects for the feline.  

Dennis’ actual birthday was May 26, 1952, meaning that Dennis the Cat Day is being held just two days after the mascot would have turned 71.

The Old Idaho Penitentiary and the Idaho State Historical Society invite the public to celebrate Dennis the Cat and to encourage support for the nonprofit pet community in Idaho.

General admission to the event is $10 per person, or it is free for members of the Idaho State Historical Society. The Prison Pets presentation at the event is free to attend with a donation of pet food to either the Idaho Humane Society or Simply Cats, both of which are locally based no-kill animal shelters.