A captivating study of US state secrecy that examines how officials use it to hoard power and prevent meaningful public oversightThe United States was founded on the promise of a transparent government, but time and again we have abandoned the ideals of our open republic. In recent history, we have permitted ourselves to engage in costly wars, opened ourselves to preventable attacks, and ceded unaccountable power to officials both elected and unelected. Secrecy may now be an integral policy to preserving the American way of life, but its true costs have gone unacknowledged for too long. Using the latest techniques in data science, historian Matthew Connelly analyzes the millions of state documents both accessible to the public and still under review to unearth not only what the government does not want us to know, but what it says about the very authority we bequeath to our leaders. By culling this research and carefully studying a series of pivotal moments in recent history from Pearl Harbor to drone strikes, Connelly sheds light on the drivers of state secrecy-especially consolidating power or hiding incompetence-and how the classification of documents has become untenable. What results is an astonishing study of power: of the greed that develops out of its possession, of the negligence that it protects, and of what we lose as citizens when it remains unchecked. A crucial examination of the self-defeating nature of secrecy and the dire state of our nation's archives, The Declassification Engine is a powerful reminder of the importance of preserving the past so that we may secure our future.