This phrase is closely connected with President Harry S. Truman. How?
President Truman's secretary, Rose Conway, sent a thank you note to Mr. Schilder for the sign shortly after the White House received it.
The bottom of the sign, which is rarely seen, is painted with "El Reno," the name of the prison that made the sign. The name of the inmate who made the sign is unknown.
After he left office, Mr. Truman ensured that the sign would be on exhibit at his Presidential library and museum. Here Mr. Truman is sitting in the Oval Office replica in the Library, shortly before it opened, with the sign on the desk.
Harry S. Truman Presidential Library and Museum