Historical Significance: The Yuma Territorial Prison was the first state penitentiary in Arizona. On July 1, 1876, the first seven inmates entered the prison and were locked into the new cells they had to build themselves. The prison was under continuous construction, with labor provided by the prisoners. Over the next 33 years, the prison would become home to 3,026 prisoners. When the prison ran out of land to build on, a new facility was built in Florence, Arizona. On September 15, 1909, the last prisoners were transferred to Florence. The prison is on the National Register of Historic Places.