Mass incarceration costs the US more than $80 billion in a year. That's how much corrections expenditures cost the US — mostly state and local governments — in 2010, according to the Hamilton Project.

In a tweetstorm following his speech at the NAACP's 2015 national convention, President Barack Obama provided a different way to look at that cost by explaining what that $80 billion could go to:

America is home to 5% of the world's population, but 25% of the world's prisoners. — President Obama (@POTUS) July 14, 2015

America keeps more people behind bars than the top 35 European countries combined. — President Obama (@POTUS) July 14, 2015

In 1980, there were 500,000 people in American jails. Today, there are 2.2 million. Many belong. But too many are nonviolent offenders. — President Obama (@POTUS) July 14, 2015

The $80 billion we spend each year to keep people incarcerated could pay for universal pre-K for every 3-year-old and 4-year-old in America. — President Obama (@POTUS) July 14, 2015

The $80 billion we spend each year on incarcerations could double the salary of every high school teacher in America. — President Obama (@POTUS) July 14, 2015

We could eliminate tuition at every public college and university in America with the $80 billion we spend each year on incarcerations. — President Obama (@POTUS) July 14, 2015

Mass incarceration doesn't work. Let's build communities that give kids a shot at success and prisons that prepare people for a 2nd chance. — President Obama (@POTUS) July 14, 2015

As Obama noted, some people will always need to be in prison, and the $80 billion includes the cost of probation and parole, so that full sum isn't going to be freed up even through really extensive criminal justice reform. But by directly comparing incarceration with other expenditures, Obama is making a point many criminal justice experts now agree with: Mass incarceration reached the point of diminishing returns by the 1990s — there are only so many serious criminals out there, and by then the people getting put in prison weren't people who'd be committing crime after crime on the street. So it would be better for the US to spend money on other measures, some of which could even do a better job at fighting crime.