On the Road, From the Postal Web to Lincoln Highway
Part 8 in a series on global information design continuing the history of road transportation diagrams
3.1 Transportation On the Road, Part 2 (catch up on Part 1)
Visualizing the 18th and 19th-Century Postal Web
Nicolas Sanson, who designed the first map of France’s postal network, is recognized today as the father of French cartography . He began drawing maps in his hometown of Abbeville. His depiction of France’s network of post roads was published in Paris in 1632 by the engraver Melchior Tavernier who, omitting Sanson’s name, gave himself credit for the work. Sanson later relocated to Paris, took back control of the plates and included it in his Atlas du Monde (1668), which covered Asia, Africa, and the Americas as well as Europe.
Postal roads were the kingdom’s information highways. Tavernier supplied Sanson with 623 locations along with the distances used to calculate the cost of sending letters. Sanson responded by plotting and connecting the post locations onto a network of rivers and coastal outlines. Though its title reads “Carte géographique des postes qui traversent la France” (A geographic map of the post roads that traverse France), it’s focus is transportation. Such a visualization made it possible for anyone to plan and estimate the time needed for a person or a message to travel from one location to another.
Sanson uses a coding system similar to Etzlaub in which the marks themselves encode the distances. Between each circle is a series of dashes indicating the distance between posts. The engraver added a note “Au Lecteur” (To the Reader) on the right side of the map. In the spirit of crowdsourcing, he invited local people reading the map to inform him of any additions or changes to the network. There are no records that Tavernier’s note resulted in revisions to the map.
Though the diagram is focused on the area served by the King’s postal system, some major towns outside the network are included without connecting roads. Boundary lines show the political edges of France, with some roads connecting to foreign cities . These are the same cities — London, Brussels, Geneva, Turin — served by France’s current high-speed train network.
The Anglo-American Web
One hundred fifty years later, the first comprehensive road map of North America also depicted the web of roads used by a postal network. A map of the United States exhibiting post roads & distance was the first of a series of maps created by Abraham Bradley, who served as First Assistant Postmaster General during America’s first decades. It appeared in 1796 to document the transportation network that connected the former English colonies.
The roads connect 450 post offices concentrated along the coastal plains and river valleys. To indicate distances, numbers appear between towns, a coding system that carried over to later road maps. Three types of roads — Post Roads, Post Roads established by Contract and Post & Stage Roads — are differentiated by shading of the connecting lines. The encoding of road types by different line styles would continue to develop in future maps.
Bradley created the diagram by combining information from commercially available maps, military surveys and distances from reports by local postmasters. The print was distributed to post offices and sold to the general public . The elaborate table that fills the space off the Atlantic coast, “Progress of the Mail on the Main Line,” lists the stages connecting the northernmost town of Brewers, Maine to the southernmost town of St. Mary’s, Georgia. The chart indicates the time of day when the north- and south-bound mail arrives and leaves in each town. This gives the reader a schedule of how long it will take for a letter to travel from town to town. A letter leaving from Portland, Maine at 6 am on Wednesday will take eight days to arrive in Philadelphia the following Wednesday at 7 am.
Show Me the Road to Get There
The examples so far have visualized overland travel as potential pathways through a network of a region’s roads. The same problem can be visualized as a single road that leads from our present location and reaches our ultimate destination. A different type of transportation diagram is needed to support a pre-determined journey following a single road.
Sabatele, a man from Tanzania (at the time German East Africa), was hired by the German scientist Karl Weule to support his travels. Sabatele drew a map of the caravan route from the inland start of their journey to the Indian Ocean, which Weule chose to reproduce in his book Native Life in East Africa . In modern European practice, transportation diagrams had become an external rather than an internal representation of spatial understanding. We expect such diagrams to be a record, rather than a performance. Many indigenous peoples who lived by their knowledge of trade networks instead relied on internalized maps and performative means to support overland travel. Weule’s decision to solicit drawings from his African employees with no European education, to see what they could do, is an example of this. European literature is filled with examples of explorers expressing profound surprise when indigenous people, often at the explorer’s request, perform their spatial knowledge by drawing maps on the ground or on supplied materials .
Weule was able to decode each of the dots, circles and connecting lines in the drawing through discussion with the men he employed. Reading right to left, the visualization represents roads from several possible points of origin on the shores of Lake Tanganyika, Lake Victoria or the area between the lakes crossing rivers, swamps, mountains and deserts, to arrive at the various markets of Dar es Salaam on the Tanzanian coast.
The map is oriented with south at the top and the coast on the left. In this case, the “legend” of the route map was the context of the request to visualize the caravan roads and share that knowledge through discussion. The lines connecting the circles represent the roads. The lines crossing the road represent natural barriers — rivers and swamps — while the circles inside circles represent places. In this case, the angles of the connecting lines carry useful directional information.
John Ogilby’s route maps of Britain are strikingly different from this East African example, yet they share many of the same informational characteristics. Ogilby was neither a caravan driver nor a great traveler. At different periods of his life, he was an English court entertainer in dance and theater, a writer of poetry and classical translation, and a major London book publisher. His fortunes rose and fell and rose again during the turmoil of the English Civil War and Restoration. His calling as an information designer came at late in his life when, at the age of 70, he held the title of Cosmographer to the King in the court of Charles II. In the few years that remained to him, he produced atlases of Africa, America, Japan, China, and Asia, then planned to write and publish Britannia, a multi-volume work that would include a comprehensive history and description of England and Wales.
Britannia, volume the first  was the only part of this project that was completed. When the book appeared in 1675, it was the first visualization of an English road network that had previously been described only as lists of place names along selected roads. As part of that project, he participated in a survey of all the roads in the kingdom. Distances were measured by a man pushing a perambulator or measuring wheel beside a mounted surveyor recording the distances. This measuring of the road is illustrated in his book’s frontispiece and the cartouche of several maps .
Ogilby transformed these itineraries into transportation diagrams, introducing a set of innovations. First, the maps employed the same unit — a “statutory mile” — for all distances. Previous itineraries had used local miles, the length of which varied from region to region. Second, the maps were drawn to a uniform scale of one inch to one mile. Each two-page spread contained seven strips, each strip representing about 10 miles. To accommodate this physical constraint, he introduced a third innovation fundamental to the strip-map format. He drew each road continuing straight from the bottom to the top of the strip, and rotated the compass rose, rather than the road itself, to indicate turns in cardinal direction. Joel Katz credits Ogilby with introducing the “heads-up” technique [9, pp. 174–175] to emulate the traveler’s experience that the road always continues straight ahead.
A fourth innovation was the way he combined different illustration formats to represent information along the road. Major cities are shown with a street plan while lesser towns are shown as tiny buildings — a row of houses, a castle, a church. Landmarks along the road — a rill, a brook, a hill or bridge — are drawn and noted in text. The orientation of hills shifts to fit into the design of the page.
What to Expect Along the Road
The Oregon Trail maps by John C. Frémont and Charles Preuss were designed to support a very specific kind of travel: mass migration. Topographical map of the road from Missouri to Oregon, commencing at the mouth of the Kansas in the Missouri River and ending at the mouth of the Wallah-Wallah in the Columbia  is a set of seven maps published in 1846 by the US Printing Office. It represents the trail along with geographical, meteorological and political information gathered by a team led by Frémont. The team’s mission was to document the best route for people migrating from the Missouri region to the Pacific Northwest. Charles Preuss, a surveyor, and cartographer who had learned both skills in his native Prussia before emigrating to the US, was part of Frémont’s team. They followed the wagon trains along a trail that had been in use for decades but not yet documented, leaving Westport, Missouri in early June and arriving in current Washington state in October 1842.
In the maps they produced, the journey starts on the right and continues to the left, with latitude and longitude lines on each section skewed to indicate shifts in cardinal direction. The consistent scale is 10 miles to the inch. Detailed topography is restricted to the area around the trail. While some connections to side trails are shown, the design was meant to prevent travelers from straying off the trail. A chart of “meteorological observations” reported the sort of weather information travelers could use to set their expectations: morning and evening temperature, altitude and wind for each day of Frémont’s 1842 journey.
Each section also included “remarks” on what to expect concerning the local status of resources migrants would need to survive: water, grass to feed the horse and oxen, fuel for fires and game for food. The trail crossed the territories of many indigenous tribes and their presence was noted on both sides of the trail. The migration generated massive ecological and political changes in the northwest, threatening the autonomy and survival of these tribes. In addition to temperature and wind, the “remarks” address the political balance of power per section, such as this from Section IV:
6. Indians. Between the Red Buttes and Green River, the war ground of the Indians, particular attention should be paid as to guards and watches.
The rest of the space is taken up with quotations from Frémont’s lengthy report, providing the traveler with local color about each section of the journey.
The Age of the Automobile
Despite the profound shift from animal power and steam engines to gasoline engines in the early 20th century, the advent of the automobile did not inspire any major information design innovation. The earliest national US road maps, produced by private automobile associations around 1918, employed the same geographic formats that had worked for centuries. Roads were drawn as lines over scaled geography defined by coastline and rivers.
Early examples such as Automobile Road Map of the United States showing Transcontinental Routes and other Main Highways,  published by the Automobile Club of Southern California (ACSC) resembled Etzlaub’s link-node diagrams. There are similarities: every dot on the map represents a named town, towns are connected by roads and colors are used to tell the traveler when they are crossing state boundaries. But the distance between towns can no longer be read from the lines themselves. By modern convention, the scale on the map mathematically reproduces distances between points.
For travelers who want the local details, auto clubs published strip maps to guide the driver along predetermined routes. This example from a set of ACSC strip maps for the Lincoln Highway  displays many of the same features found on Ogilby’s maps. Lincoln Highway was the main route from New York to San Francisco. So that the road can always be depicted in a lateral direction, the cardinal direction is indicated by a compass pointing north on each strip map. Relevant boundaries are shown such as rivers, railroads and county lines. The relevant services are now garages and hotels.
By the end of the 20th century, road maps had become dense collections of any and all information potentially relevant for a traveler. This small section from a Michelin departmental map of France, self-described as “detailed and ultra-readable,” illustrates how dense the coding has become. Over a base of the regional geography, the designer combines color and line width to reproduce roads of all sizes, then adds layers of scenic drives and viewpoints, cultural sites and monuments referenced in tour guides, recreation facilities, and distances. It is all there if you can learn how to visually parse the coding.
In all these examples, the designer is visualizing a selection of information to support a hypothetical journey. Even the strip maps are not customized for a precise point of origin, the exact destination or the road conditions of a specific day. But what if a transportation diagram could visualize the best route for a specific journey at a specific time? What if that diagram could show alternate routes and where to expect delays, along with the best route based on your preferences for travel time, tolls and type of road?
The development of real-time navigation systems has modified the question a transportation diagram can be expected to answer. Routing algorithms processing road condition data have changed “getting from here to there” into “the best way right now.” Representations of traffic slow-downs, road construction and accidents are now prominent features in the information design. Digital rendering makes the choice of what and how much to label algorithmic, tied to one of 16 levels of magnification. The digital transportation diagram now tells you how long it will take, a number that is recalculated as road conditions change during travel. Once travel begins, the visualization continually rotates, tracking the traveler’s direction in space. You are always going straight ahead towards your destination.
In many parts of the planet, the infrastructure of cell towers, navigation satellites and mobile devices have made it possible for travelers to request overland transportation diagrams when and where they need them. Our GPS navigation systems knows where we are. The designer still has to represent information the traveler needs to make decisions: which road to choose, which way to turn. We may look at printed roadmaps before or after a journey to support a mental model of space, but we increasingly rely on ephemeral digital route maps to guide our overland travel.
Next: Travel on the Sea and Through the Air
The next part of Transportation will examine the history of diagrams that help us travel across the sea and through the air.
Global Information Design: an overview of the series
Global information design embraces the visualizations of qualitative data such as expressions of social hierarchy, cultural beliefs, and values, as well as visualization of quantitative data, such as economic trends and scientific explanation. We can broaden our view of information design by following the pathways of its intended use. Exploring the history of how we visualize cosmology and timelines, transportation networks and family lineage, is as informative for current data visualization practice as the mastery of programming libraries and cognitive science. Studying examples of information design from many time periods and many cultures helps us understand how we shape patterns of difference into hierarchies and networks to create that chart, story, or graphic from the patterns that connect.
Part 8: On The Road, from the Postal Web to Lincoln Highway (this article)
Visualizing Overland, When All Roads Led to Rome
Part 7 in a series on global information design explores transportation and road maps
City Maps: Ways to View the Polis
Part 6 in a series on global information design explores historical maps that represent the ways we view the city
Kingdom Maps: Drawing the Boundary Between Us and Them
Part 5 in a series on global information design explores historical maps that superimpose political influence onto…
Maps = Eyes + Imagination, Envisioning the Known World
Part 4 in a series exploring global information design looks back at some of the earliest maps of the world
Cosmology in the Small
What pre-Columbian migration maps and historic theological texts can teach us about global information design
Diving into Global Information Design: Cosmology in the Large
Classification is an intellectual act, performed as often in the name of theology as in the name of science.
Global Information Design: A New Framework for Understanding Data Visualization
Establishing a new category of historic data visualization by exploring the semiotics of lines and patterns.
 M. S. Pedley, “The map trade in Paris, 1650–1825,” Imago Mundi, vol. 33, no. 1, pp. 33–45, Jan. 1981.
 N. Sanson and M. Pastoureau, Atlas du monde. Paris: Sand & Conti, 1988.
 L. Caldwell and M. Buehler, “Picturing a Networked Nation: Abraham Bradley’s Landmark U.S. Postal Map,” The Portolan, Journal of the Washington Map Society, no. 77.
 K. Weule, Native life in East Africa: the results of an ethnological research expedition. New York: Appleton, 1909.
 T. J. Bassett, “Indigenous Mapmaking in Intertropical Africa,” in Cartography in the traditional African, American, Arctic, Australian, and Pacific societies, D. Woodward and G. M. Lewis, Eds. Chicago: University of Chicago Press, 1998, pp. 24–48.
 The Decolonial Atlas, “East African Ground Maps,” The Decolonial Atlas, 21-May-2016.
 J. Ogilby, Britannia, volume the first, or, An illustration of the kingdom of England and dominion of Wales : by a geographical and historical description of the principal roads thereof : actually admeasured and delineated in a century of whole-sheet copper-sculps : accomodated with the ichnography of the several cities and capital towns : and compleated by an accurate account of the more remarkable passages of antiquity, together with a novel discourse of the present state. London: Printed by the author, 1675.
 G. C. Dickinson, “Britain’s First Road Maps: The Strip-Maps of John Ogilby’s Britannia, 1675,” Landscapes, vol. 4, no. 1, pp. 79–98, Apr. 2003.
 J. Katz, Designing information: human factors and common sense in information design. Hoboken, New Jersey: Wiley, 2012.
 J. C. Fremont and C. Preuss, “Topographical map of the road from Missouri to Oregon, commencing at the mouth of the Kansas in the Missouri River and ending at the mouth of the Walla-Wallah in the Columbia.,” United States Congress, Baltimore, 1846.
 R. Moore, “1920s Road Trip: The Lincoln Highway in Strip Maps,” Worlds Revealed: Geography & Maps at The Library Of Congress, 18-Feb-2018.