Published under a shared pseudonym in New York newspapers, these 85 essays by Hamilton, Madison, and Jay were a political campaign in essay form — a sustained, closely argued case for why the fractious new states should ratify the U.S. Constitution rather than risk collapsing into separate, weaker nations. Written fast, under real political pressure, they remain the clearest explanation ever written of what the Constitution's authors actually intended, and why they built the government the way they did.
Still cited by the U.S. Supreme Court more than any other historical source when interpreting the Constitution — essential reading for anyone who wants to understand American government from its own founding argument.