"As many as 4 million people hold "top secret" security clearance, of which 500,000 are private contractors. One reason for this trend is that the U.S. government has become so reflexive about classifying information, much of which is not nearly as sensitive as an NSA spying program, that clearance are required even for totally banal work."

https://www.washingtonpost.com/news/worldviews/wp/2013/06/12...