Taken together, it looks like momentum. And it undoubtedly is. But the political progress belies a troubling, substantive fact: The federal prison system, which is what all these national lawmakers are talking about when they talk about reform, is relatively small, and fixing it would not have any direct effect on the state and local systems in which the vast majority of American inmates are incarcerated. As Obama underscored in yesterday’s speech, there are more than 2.2 million people currently behind bars in the United States, including about 700,000 in local jails. According to the latest numbers from the Bureau of Justice Statistics, just 215,866 of them are serving in federal prison.

So what is the federal government’s role in ending mass incarceration, exactly, given that it only has jurisdiction over about 10 percent of the nation’s prisoners? To find out, I called a number of experts and asked them whether all the excitement we’re seeing around reform at the national level is warranted. They told me that while it’s true federal legislation would only directly affect a relatively small number of prisoners, there is nevertheless significant value, both real and symbolic, in Congress and the president joining forces on this issue.