The good news is that's about 10% less than in 2009 (the peak prison population year).
The bad news is that the United States still has more people behind bars than any other nation in the world -- both in total numbers and the per capita ratio.
Why? Are Americans more lawless than the citizens of other countries? Not at all. People are pretty much the same all over the world.
One reason is that the United States has decided that it can solve social problems (drugs, prostitution, etc.) by locking people up. Another reason is that, although some other countries follow that fallacious reasoning, the U.S. gives much harsher sentences for that conduct.We need to change that.
Don't get me wrong. Prisons are necessary to deal with true criminals -- those who hurts people or take their property. But we must stop locking people up just because we don't like their conduct (even though that conduct doesn't harm other people).
We need to depend more on treatment (voluntary) and education to treat social ills. We need to use probation more for non-violent crimes, and use shorter sentences when probation fails. And we need to make our prisons more attuned to rehabilitation and make sure once released, a person can get a decent job.
We can do much better. Sadly though, our politicians don't understand the reform that is badly needed.