The United States government spends about $2.7 million per prisoner per year to operate the Guantanamo Bay detention facility in Cuba, the Washington Post reports.

That estimate comes from a recent study by the Miami Herald’s Carol Rosenberg, who has covered Gitmo since 2002. According to Rosenberg, the U.S. will spend $454 million this year to maintain the facility and pay troop salaries, among other fees — a little under half a billion dollars.

With only 166 prisoners, that works out to an annual cost of about $2.7 million per detainee. For a point of comparison, California spends an annual $47,000 per prisoner, according to a 2010 study from that state’s government.

According to the Post, Rosenberg’s study serves as a reminder of the tremendous cost and inefficiency of running Gitmo and why the detention facility has been such a thorn in the side of the Obama administration.

In January 2009, President Barack Obama issued an executive order to close the camp, but the process has been stymied at every turn by a veritable Gordian knot of political and legal obstacles as well as national security concerns. Finding a place to put the prisoners if Gitmo were shuttered has been a contentious issue in both domestic politics and international diplomacy.

“I think for a lot of Americans, the notion is out of sight, out of mind,” Obama said at a press conference in April, insisting he would resume efforts to close the prison. “I’m going to go back at it because I think it’s important.”