Some 2.4 million persons currently hold security clearances for authorized access to classified information, according to a recent Government Accountability Office report (pdf) to the House Intelligence Committee, citing an estimate from the security clearance Joint Reform Team. This figure does not include “some of those with clearances who work in areas of national intelligence,” the GAO noted (at p.1).
An accurate tally of the number of cleared government employees and contractors — as opposed to a round-number estimate — is not currently available anywhere in government. The House version of the FY2010 intelligence authorization act (sec. 366) would require an annual report that indicates the number of individuals with security clearances.
In 1993, an estimated 3.2 million persons held security clearances, according to a 1995 GAO report (cited by the Moynihan Commission, chapter 4).