While hunting for a different item for a Civil War research request, I came across a thin booklet in our archives. It lists Pennsylvania soldiers who were buried at Andersonville, the notorious prison in Georgia.
The booklet lists the soldiers in alphabetical order. It also includes their regiment, cause of death, date of death, and grave number. The front of the booklet also includes a short note to Pennsylvania Governor Curtin dated July 1, 1865. It's from the Surgeon General of Pennsylvania, Joseph A. Phillips, who explains he compiled this list at the request of the Governor.
Due to horrendous conditions, nearly 13,000 prisoners of war died at Andersonville. Some, like J. Carr, were from Montgomery County, Pennsylvania. When looking at the cause of death in this booklet, just about all of them died from disease as a result of the unsanitary conditions at the prison.
If you thing you have a Pennsylvania ancestor who might have died at Andersonville, definitely stop by HSMC to look at this booklet. The National Park Service also has some resources to help people learn more about their ancestors who are buried in the National Cemetery in Andersonville. You can follow this link to their website: https://www.nps.gov/ande/learn/historyculture/documenting_union_pows.htm