Between Pizzagate, QAnon, and the now ubiquitous cries of fake news, it's tempting to think that we're living in an unprecedentedly fertile age for conspiracy theories. But the sad fact is that these narratives of suspicion-and the delusional psychologies that fuel them-have been a constant presence in American life for nearly as long as there's been an America. In this sweeping book, Thomas Konda traces the country's obsession with conspiratorial thought from the early days of the Republic up to our own anxious moment. Conspiracies of Conspiracies details centuries of sinister speculations-from anti-Semitism and anti-Catholicism to UFOs and reptilian humanoids-and their often incendiary outcomes. Rather than simply rehashing the surface eccentricities of such theories, Konda draws from his unprecedented assemblage of conspiratorial writing to crack open the mindsets that lead people toward these self-sealing worlds of denial. What is distinctively American about these theories, he argues, is not simply our country's homegrown obsession with them but their ongoing prevalence and virulence. Konda shows that conspiracy theories are less a harmless sideshow than the dark and secret heart of American political history-one that threatens to poison the bloodstream of our increasingly sick body politic.