A comparative spatial history using GIS, this article examines the similar and differing effects of railway expansion on the growth of postal communications in Great Britain and France from 1830 to the eve of the Great War. It argues that the modern Postal Age in Great Britain and France began in the 1830s. In Britain in 1839, the Parliament obligated private railway companies to convey the Royal Mail throughout the kingdom at reasonable rates. Thereafter, the expansion of postal services and railway networks went hand in hand. Over the years, thousands of new post offices were established and were closer to rail stations than before. As the years wore on the geography of postal communication expanded greatly and by 1914 the majority of rural districts became part of the system of regular, daily mail. In France, a country four or five times larger than England and Wales with a relatively vast rural population, the task of modernizing postal service was a greater challenge. The inauguration of a “rural service” in 1829 employed some 5,000 men as postal carriers to deliver and collect mail throughout the countryside. Thereafter, their numbers grew as new post offices were established to serve villages and small towns with mail deliveries every other day. In the 1880s, under the Third Republic, the state greatly expanded the postal service, deeming it a national mission. It was then that the growing rail network came to shape the national geography of postal service. Hence, at the turn of the century the patterns British and French postal expansions converged.