In the long history of abuses committed against patients in state run mental facilities, Byberry in Philadelphia might be the worst in existence.
The allegations against the staff at Byberry ran the entire gauntlet of atrocities: assault, murder, sexual assault, illegal experimentation and terrible conditions overall.
In 1919, two orderlies killed a patient by strangling him to death. The orderlies claimed to have PTSD after fighting in the war, so not only were they not prosecuted for it, they were both given raises to continue working at the hospital.
There was a children's ward at Byberry, but it was severely understaffed. Instead of hiring more support staff, the institution started putting the hospitals "most stable" patients in positions as attendants for the kids. I don't need to spell out what happened to explain how bad of a decision that was. Many of the kids at Byberry were sexually assaulted by these attendants.
Thorazine was created by the Smith Kline-French Company. They partnered with Byberry to test the drug on patients there. Many of them died, and few patients had the mental capacity to give consent, nor did they have any family members who would notice this type of action being taken against the patients.
Terrible medical treatment
Imagine having to go in for an invasive medical procedure but having pain killers denied to you. Back then doctors believed that mental patients didn't feel pain the same way as "normal" people, so they would often operate on them when they could feel everything happening to them.
Gone with the wind
When the hospital was finally shuttered for the final time it caused several other problems. With no where else to go, several patients committed suicide, while those that were still alive were quite literally let out the front gates with no restrictions. Philadelphia was suddenly home to 2500 former mental patients who now had no supervision.
Check out this documentary focusing on mental illness, specifically Byberry Mental Hospital.