Postal services have always been a core foundation of advanced civilizations. Hence the U.S. Postal Service is one of the few federal agencies explicitly authorized by the Constitution, based on the understanding that an open and prosperous society relies heavily on the free-flow of information.
We take for granted that until very recently, mail was the world wide web of the day—the sole means in which everyone could communicate and access information on equal footing. That is why the USPS is still relevant to this day, since it is the only service to be fully egalitarian by guaranteeing equally cheap delivery to everyone, regardless of where they live. No wonder it is the most popular federal agency in the country.
There is a lot of historical precedence for this. In the fifth century BCE, Darius the Great of Persia established the earliest confirmed postal service, the Angarium, to consolidate what was then the largest empire in history. It facilitated trade, communication, and cultural exchange at a rate of efficiency that was unprecedented at the time. Remnants of this mail infrastructure are still around.
The riders of the Angarium were well regarded for their honesty, discipline, and efficiency; they could deliver a message across a distance of almost 1,700 miles in just one week—the normal speed was three months! Greek historian Herodotus wrote that:
There is nothing in the world that travels faster than these Persian couriers. Neither snow, nor rain, nor heat, nor darkness of night prevents these couriers from completing their designated stages with utmost speed
Other empires borrowed from the Persians, or soon realized on their own the vital nature of postal communications. In the first century CE, the Romans established the Cursus publicus to provide special light wagons and faster horses for mail. Genghis Khan created the sophisticated “Ortoo” system for his massive Mongol Empire, which consisted of a complex chain of relay stations 20–40 miles apart, each with a messenger ready to complete the next leg of the journey; with spare horses, food, shelter, this ensured information was constantly on the move without each messenger getting tired. Hence why the famous Silk Road was even a thing!