Final answer:
The United States operates the largest jail system in the world, with the highest incarceration rate and over 2.3 million people in various correctional facilities as of 2018.
Step-by-step explanation:
The entity that currently operates the largest jail system in the world is the United States. The U.S. has seen a massive increase in its prison and jail populations since the 1980s, particularly during the war on drugs. The incarceration rate in the U.S. is the highest globally, with more than 700 inmates per 100,000 people. As of 2018, approximately 2.3 million individuals were incarcerated in various facilities across the country, including state and federal prisons as well as local jails. This figure is part of a larger corrections system which also includes those on parole or probation, bringing the total to about 6.4 million people under correctional supervision. American policy in comparison to other industrialized nations reveals a heavy reliance on mass incarceration for crime prevention, leading to significant numbers of people imprisoned for minor offenses and for longer durations than their counterparts in many other countries.