How Did Postal Systems Develop? Relay Riders to a Flat Rate

The earliest organised postal arrangements were state communication networks and several were remarkable. The Persian system described by Herodotus used relay stations a day's ride apart, with riders and horses waiting so that a message continued without pause, and his description of couriers stopped by neither snow nor rain became a much later postal motto. Rome's cursus publicus maintained stations along the road network for official traffic, requiring local communities to supply horses and lodging, which was a substantial burden. The Mongol yam network operated on a similar principle across an enormous territory, with stations supplied by surrounding populations and riders carrying a tablet authorising their passage, which Marco Polo described in detail. China, the Inca and the Islamic caliphates all maintained comparable systems. What they shared was purpose: these were instruments of administration and military control, carrying orders and intelligence, and private correspondence travelled by whatever ad hoc means people could arrange, typically by giving a letter to a traveller going in roughly the right direction.

The transition from state courier to public post happened gradually and then abruptly:

• •Merchant and guild networks in medieval Europe carried commercial correspondence privately, and university couriers served scholars
• •The Thurn und Taxis family operated a postal service across the Holy Roman Empire from the late fifteenth century under imperial privilege, running it as a business for centuries
• •State monopolies were established in several countries in the sixteenth and seventeenth centuries, partly for revenue and partly because controlling the post meant being able to read it, which was done systematically in dedicated offices
• •Charges were paid by the recipient rather than the sender, calculated by distance and by the number of sheets, which made postage expensive, unpredictable and frequently refused
• •That system invited evasion, since a prearranged mark on the outside could convey a message that the recipient then declined to pay for, which was widespread
• •Rowland Hill's 1837 pamphlet argued that the cost of carrying a letter was trivial compared with the cost of calculating and collecting variable charges, and proposed a uniform rate prepaid by the sender

Hill's reform was adopted in Britain in 1840 and the change was structural rather than incremental. A single low rate for any distance removed the accounting entirely. Prepayment by the sender removed the refusal problem and the costly attempts to collect. And the adhesive stamp, introduced to evidence prepayment, was an elegant solution to a practical problem that became the most widely imitated administrative invention of the century. Volumes rose immediately and enormously, which vindicated the argument that demand had been suppressed by price and friction rather than by lack of need. The consequences ran well beyond convenience: cheap reliable correspondence supported commerce, allowed families separated by migration to remain in contact, underpinned the growth of mail order and of the periodical press, and made written communication a normal part of ordinary life rather than a privilege. Other countries adopted the model within a few decades.

Sending a letter abroad initially required bilateral treaties between every pair of countries, producing a tangle of rates and rules. The Universal Postal Union, established in 1874, resolved it with a set of principles that are still in force: each country's post is treated as a single territory for transit, each keeps the postage it collects rather than settling for every item, and members undertake to forward each other's mail. It is one of the oldest international organisations and among the most quietly successful. The terminal dues system, governing what a destination country is paid for delivering incoming mail, became contentious as e-commerce made cross-border parcels a major flow and as some countries argued the rates favoured others, prompting renegotiation. The letter itself has declined steeply with electronic communication, while parcel volumes have grown enormously, so postal operators have shifted from a network built around daily letter delivery to one built around tracked parcels and last-mile logistics, which is a different business with different economics.

Early postal systems were state instruments, using relay stations and commandeered horses to carry official orders, with private letters travelling by improvisation. Charges paid by the recipient and calculated by distance and sheets made correspondence expensive and widely evaded. Rowland Hill's uniform prepaid penny rate in 1840, evidenced by an adhesive stamp, removed the accounting and volumes rose immediately. The Universal Postal Union settled international exchange in 1874 with principles still in use.