"As concern in the United States has grown over the number of people behind bars, policymakers and the public are turning their attention to addressing the decades-long growth in the number of people held in the country’s more than 3,000 locally run jails—county or municipal detention facilities that primarily house people who have been charged but not yet convicted of a crime (known as the “pretrial” population), and those sentenced to a short term of incarceration, usually under a year. With local jail populations swelling from 157,000 on any given day in 1970 to over 700,000 people in 2015, there are now an astronomical number of jail admissions annually—nearly 11 million—prompting many to question whether local jails have grown too large, and at too high a cost for the communities they serve. This has in turn focused efforts among policymakers and the public to better understand and reform the size, scope, and distribution of local incarceration."