The U.S. postal system was the nation's largest communications network in the nineteenth century. By the close of the century the U.S. Post had extended its reach into nearly every city, town, and hamlet in the country. No other public institution was so ubiquitous and so central to everyday life; dropping off a letter or checking for mail at the local post office was a ritual shared by millions of Americans from Connecticut to Colorado. This visualization maps the spread of the postal network on its western periphery by charting the opening and closing of more than 14,000 post offices west of the hundredth meridian.
The stacked bar chart along the bottom is a timeline of post office openings (dark blue) and closings (light blue), year by year. Users can click-and-drag to select different periods of years to visualize the network's geography at any point in the late nineteenth century. You can clear out your selections by clicking "Reset Map."
Buttons at the top of the map allow you to toggle between two views. "Duration View" offers a snapshot of post offices colored brighter or darker according to how long they were in operation for a given period of time. "Status View" shows what happened to post offices within the selected timespan - whether they opened, closed, or continuously operated for the entire period.
Hovering over an individual post office will display its name and the years it was in operation.
The map uses data compiled by postal historian and philatelist Richard Helbock in United States Post Offices, Volumes 1-8. We extend our gratitude to Richard Helbock for his incredible work to compile this data.
Three disclaimers are in order. First, many post offices are missing from the map. We attempted to look up the location of every post office in the Geographic Names Information System (GNIS), but we couldn't locate many of the offices. In order to capture the incomplete nature of our data, the sidebar displays how many post offices are successfully mapped for a given time period and how many offices are missing from the map. Second, we have not captured when an office changed names. A name change shows up as if it were a brand-new post office, with the old office "closing" and the new office "opening," even if it was the same post office in continuous operation. Finally, the closing date of an office represents a final date at which an office ceased to operate. Multiple openings and closings of the same office are not represented.
This visualization was built using D3.js by Jason Heppler, Jocelyn Hickox, and Cameron Blevins as part of the Geography of the Post project at Stanford's Center for Spatial and Textual Analysis. Special thanks to Tara Balakrishnan for her initial work and to Elijah Meeks for additional technical help.
The map works best in modern browsers, especially Safari or Chrome.