McNair Indefinite Detention Center for Parahuman Offenders
The McNair Indefinite Detention Center for Parahuman Offenders, more commonly known as The Vault, is the highest-security prison in the United States, and likely the world. Opened in 1992, the facility is a one-way ticket for parahumans sentenced to life in the US (as well as Canada through treaty).
It was created following a Supreme Court decision that effectively made capital punishment illegal for parahuman offenders. Its exact location is kept a secret, but is known to be somewhere in the Nevada desert. To date, zero prisoners sentenced to the facility have successfully escaped. For security reasons, communication or other contact with prisoners is forbidden.
Due to the nature of the facility, some believe that it's merely a front made by the government to bypass the loophole created by the Accords, and that in reality those condemned to the Vault are simply taken to a secure location and covertly executed. While the Parahuman Response Team, who manages the facility, strongly deny these claims, some critics wonder if a life sentence in an oubliette with absolutely no communication with the outside world is fundamentally different from a death sentence. Regardless, attempts to shutter the facility have been repeatedly shot down, and polling shows that over 70% of registered voters support the Vault remaining open.