USP Big Sandy is a high-security federal penitentiary in Martin County, Kentucky, near the town of Inez, and it has been operating since 2003. What makes its construction story unusual is the ground it was built on — a site that had been used for mountaintop removal coal mining and included a former underground mine, which meant the federal government had to spend around $40 million on environmental remediation before building even started, with more costs cropping up once construction was underway. As a high-security institution, Big Sandy holds a population convicted of more serious offenses and longer sentences, with around 1,400 men currently housed between the main penitentiary and its adjacent minimum-security camp; a notable share of inmates originate from the Washington, D.C. area due to how federal custody assignments work. Since opening, the facility has had a difficult track record with violence, including a number of stabbings and other inmate-on-inmate and inmate-on-staff incidents over the years, which is not unusual for a high-security penitentiary but is worth understanding for families keeping tabs on safety and conditions. It remains one of the more remote federal prisons, tucked into eastern Kentucky's mountains, which can make visiting logistically challenging.