Jaromir Koperski
Jaromir Koperski voted up Don Barzini's answer

The US has by far the largest number of prisons (4575); as well as the most prison inmates (2.2 million)---unless you count North Korea, which IS a prison of 25 million inhabitants. 

Saudi Arabia is currently executing more people as a function of its penal system than any other sovereign country. Other entities such as Boko … Read more

Jaromir Koperski
Jaromir Koperski voted up Walt O'Reagun's answer

Which country executes the most would be hard to say, for sure ... Since many countries ruled by tyrants or corrupt governments execute thousands of people a year - but most of them are listed as "missing" since the government doesn't actually admit to killing them.