There's no two ways about it: The United States of America and its 50 state governments love putting people in prison.
The U.S. has both the highest number of prisoners and the highest per capita incarceration rate in the modern world at 655 adults per 100,000. (It's worth noting that China's incarceration statistics are dubious, and they execute far more people than the United States. Indeed, the so-called People's Republic executes more people annually than the rest of the world combined.) Still, that's more than 2.2 million Americans in state and federal prisons as well as county jails.
On top of those currently serving time, 4.7 million Americans were on parole in 2016, or about one in 56. These numbers do not include people on probation, which raises the number to one in 35. Nor does it include all of the Americans who have been arrested at one time or another, which is over 70 million – more than the population of France.
For firearm owners in particular, the growth in this "prison-industrial complex" is troubling because felons are forbidden from owning firearms and ammunition under the 1968 Gun Control Act. As the number of laws has grown and the cultural shift for police has gone from a focus on keeping the peace to enforcing the law, more and more Americans are being stripped of their 2nd Amendment rights (not to mention other civil rights like voting – as of 2017, 6.1 million Americans cannot vote because of their criminal records). All told, eight percent of all Americans cannot own firearms because of a felony conviction.