Why is the Missouri state penitentiary prison so haunted is it because of the history behind behind the penitentiary prison or is it the stories that where told about the prison?

A lot of ppl got violent killed and executed there too

Both, to be honest.

The prison has a long ad violent history that lead to the haunting. The stories are just explanations of what happened and is happening.

Theres actually a long history of the prison. Many people were sent to death via the gas chamber, there was a giant fire and prison outbreak, people hung the court yard and a few well known criminals were housed there as well, like Pretty Boy and Bonnie Heady. There is a book about the history called "From Shanks To Shakers!"