evidence: Incarceration is the state of being confined in prison, typically as punishment for a crime. Every country in the world has a prison system of some sort, though the exact nature of that system—as well as the number of prisoners incarcerated within it—varies tremendously from country to country. The United States leads the world in total number of people incarcerated, with more than 2 million prisoners nationwide (per data released in October 2021 by World Prison Brief). This number is equivalent to roughly 25% of the world's total prison population and leads to an incarceration rate of 629 people per 100,000—the highest rate in the world. The prison populations in each U.S. state vary from one to the next, with the highest rates in Louisiana and Oklahoma. Overall, the incarceration rate in the U.S. has skyrocketed in the past decade—the prison population was a mere 200,000 in 1972, less than a tenth of today's total. However, the current rate is the lowest it has been in 20 years.