MISSOURI CIVIL WAR PRISONS
Source: www.civilwarmo.org/educators/resources/info-sheets/military-prisons
GRATIOT PRISON. The largest prisoner of war camp in Missouri was Gratiot Prison, located in St. Louis, Missouri, in a confiscated school building. Operations began in 1861, and at times, it would house as many as 2,000 prisoners. Often overcrowded, prisoners suffered, as its official capacity was only 1,200. It incarcerated not only Confederate soldiers but also sympathizers, guerrillas protected by General Order No. 100, spies and Union soldiers who had committed crimes.
MYRTLE STREET PRISON. This was originally a two-story brick building slave pen with a capacity for 100 prisoners. In September 1861, Myrtle Street became the first prison to be used by the Union and eventually housed as many as 145 prisoners.
ALTON PRISON. The Illinois state prison in Alton, Illinois, north of St. Louis that had been closed in 1857. After the Gratiot and Myrtle Street Prisons became overcrowded, Alton Prison was reopened. More than 11,000 soldiers were incarcerated, and the site experienced the highest death rate of Union prisoners due to the harsh conditions and exposure to smallpox and rubella. It is estimated that more than 1,500 Confederate soldiers perished within its confines. The prison site is in the National Register of Historic Places, and a section of the prison wall remains and can be examined on the site.
Local city prisons in use by Federal forces: Jefferson City Prison, Macon City Prison and Springfield Prison