It’s been a landmark week in the criminal-justice world, as a barnstorming President Obama pushed for broad reforms to the sentencing system and called for an end to mass incarceration. (The U.S. has roughly 5 percent of the world’s population, but a quarter of its prison population.) On Monday he commuted the sentences of 46 federal drug offenders. On Tuesday he addressed the NAACP’s national conference, delivering a sobering and expansive speech with a list of proposed reforms. And on Thursday he became the first sitting president to visit a federal prison.

“Over the last few decades, we’ve also locked up more and more nonviolent drug offenders than ever before, for longer than ever before,” Obama said in Philadelphia at the NAACP conference. “And that is the real reason our prison population is so high.”

But that’s not exactly the case. Serious prison reform — and shedding the dubious mantle of World’s Leading Incarcerator — will have to look far beyond just nonviolent drug offenders. Heavy prison sentences for drug crimes are only one of many reasons why the United States has by far the highest incarceration rate in the world.

As Obama said in his speech, there is remarkable bipartisan agreement on this issue. Even in the current polarized political climate, real reform is possible. U.S. Reps. Jim Sensenbrenner (R-Wis.) and Bobby Scott (D-Va.) and Sens. Dick Durbin (D-Ill.) and Mike Lee (R-Utah) are sponsoring bills that would reform drug-crime sentencing, restrict the use of mandatory minimums, broaden the use of probation, and increase the discretion given to judges in sentencing nonviolent drug offenders. Even the American Civil Liberties Union and Koch Industries have joined forces. They co-authored an article in Politico last week declaring their support for the Sensenbrenner-Scott bill.

It’s not clear yet how many current and future inmates would be affected by these bills — an analysis by the U.S. Sentencing Commission of the Sensenbrenner-Scott bill is expected in August or September — but let’s consider some extreme scenarios and the effect they’d have on the American prison population.

According to the Bureau of Prisons, there are 207,847 people incarcerated in federal prisons. Roughly half (48.6 percent) are in for drug offenses. According to the Bureau of Justice Statistics, there are 1,358,875 people in state prisons. Of them, 16 percent have a drug crime as their most serious offense. There were also 744,600 inmates in county and city jails. (The BOP data is current as of July 16. From BJS, the latest jail statistics are from midyear 2014, and the latest prison statistics from year-end 2013.) That’s an incarceration rate of about 725 people per 100,000 population.

Suppose every federal drug offender were released today. That would cut the incarceration rate to about 693 inmates per 100,000 population. Suppose further that every drug offender in a state prison were also released. That would get the rate down to 625. It’s a significant drop, no question — these hypothetical measures would shrink the overall prison population by about 14 percent. (There isn’t data from BJS on the most serious charges faced by those in local jails, so let’s assume that no jail inmates are released in these scenarios.)

But let’s have some international context. Even in that extreme hypothetical situation, the U.S. would still be an incarceration outlier. Even without its many inmates who are convicted of drug charges, the U.S. still leads the world in imprisoning people. Next is the U.S. Virgin Islands, with a rate of 542 per 100,000 people, followed by Turkmenistan at 522 and Cuba at 510. Russia’s rate is 463. (See the bottom of this post for the full list of international incarceration rates. The international data is from the International Centre for Prison Studies, and I’ve restricted the list to countries with a population of at least 100,000.)

Locking up drug offenders is only part of the larger story behind mass incarceration. Other reasons for the high rates include the severity of nondrug sentencing, the attitudes of judges and prosecutors, a high rate of violent crime such as murder, and rising crime rates in the 1970s and 1980s. “The increase in U.S. incarceration rates over the past 40 years is preponderantly the result of increases both in the likelihood of imprisonment and in lengths of prison sentences,” the National Research Council wrote in a report last year.

Reformers interested in ending mass incarceration — or at least in getting America’s rates in line with those internationally — will have to think far more broadly. It’s a much thornier problem than that.

