The U.S. intelligence community reports that more than 4.2 million people held security clearances last year. It's the first formal count of clearance holders and produced a much higher number than previously estimated.
The report to Congress was required by the 2010 Intelligence Authorization Act. The report says more than 666,000 government workers hold Top Secret clearances, as do more than 524,000 federal contractors. The rest have lower clearances.