United States Penitentiary Leavenworth is a federal medium security prison located twenty-five miles northwest of Kansas City, Kansas. The prison is for male inmates only. There was a time when they were going to build a prison for women on the property but then abandoned those plans. Leavenworth also a satellite federal prison camp there for minimum security male inmates.

Leavenworth penitentiary is often confused with the United States Disciplinary Barracks for military prisoners located near Leavenworth at Fort Leavenworth. The USDP at Fort Leavenworth is the only military prison in the United States and both prisons operate independently of each other. Leavenworth Penitentiary is a prison for civilians.

The prisoners at the USDP built the Leavenworth prison beginning in 1897 and worked on it for twenty-five years. In April of 1910, six prisoners escaped when they hijacked a supply train and crashed through the gates of the prison. Ironically, these six men were arrested for robbing a train. Five of them were recaptured, but one, Frank Grigware eluded recapture. Frank Grigware went to Canada where he later became the mayor of Spirit River, Alberta in 1916. In 1933 he was discovered by the Royal Canadian Mounted Police and the FBI as being an escaped prisoner but serious doubts arose about his earlier conviction so the United States declined to extradite Grigware in 1934. Frank Grigware never returned to the US and died in Canada in 1977.

Another man named Basil Banghart escaped from Leavenworth three times and then escaped from federal custody a fourth time while awaiting transfer back to Leavenworth. US Marshals had left him alone in a federal building for a few minutes so he placed a phone call to the local police. Basil Banghart claimed to the police that he was a federal agent who was assaulted and overtaken by his prisoner. Banghart told police that he was handcuffed and the prisoner had escaped. He gave a description to the police of the federal agent that was escorting him. He also told police that the agent is a dangerous and armed felon as well as a police imposter. The police arrived a few moments later and when they took the federal agent into custody, Basil Banghart escaped, during the confusion.

Some notable inmates to do time in Leavenworth include the likes of: James J. “Whitey” Bulger, the leader of the Winter Hill Gang in Boston, Massachusetts, George “Bugs” Moran, rival gangster to Al Capone in Chicago, George “Machine Gun” Kelly, underboss to the Colombo crime family John Franzese and the father to famed mobster Michael Franzese, and of course, American professional football star, Michael Vick. He was arrested for the crime of operating an interstate dog fighting ring. Also, the assassin of civil rights leader, Martin Luther King, Jr., James Earl Ray.

Leavenworth was a federal maximum security prison until 2005 when it was down-graded to a medium security prison. There is a cemetery outside of the prison walls for deceased inmates.