Before the United States was a unified nation, it was a fractured collection of isolated colonies. Information traveled at a glacial pace, moving by ship along the coast, leaving inland settlements entirely disconnected. The concept of a shared American identity was practically impossible without a way to communicate.The creation of a single, reliable overland route was a logistical nightmare. Forging a path through dense forests, hostile territories, and deep mud required immense labor and political will. Yet, the necessity of delivering a simple letter drove the construction of the most...