Electricity and Maps: Before Computers, There Were Currents and Coils
Electricity and Maps uncovers electricity's hidden hand in the evolution of mapmaking, data collection, and geographic insight. It examines the often-overlooked roles in mapmaking of long-distance telegraph lines and electric power. By focusing on the era before the digital computer and the geographic information system (GIS), the book offers a broad, surprisingly intriguing take on the history of modern cartography and the map's responsibilities in emergency management.
Development of the electromagnetic relay inspired the systematic collection of atmospheric observations across vast regions—data essential for compiling the maps used to track storms and warn of extreme weather. Electric current also supported the systematic measurement of longitude and the drafting and labeling of hand-drawn maps. And when electronic fire and police-alarm networks were initiated in the nineteenth century, maps had fundamental roles in planning coverage, orchestrating disaster response, and setting insurance rates. Over sixty facsimile illustrations and explanatory graphics enrich the discussion of how the electric power used in creating most maps is as important as the persuasive power of a few maps.
Cartographic use of electric current traces back to the nineteenth century. It began with electroplating for printing plates and telegraphy for harvesting data from the frontier. At the heart of this revolution was the electromagnetic relay, or solenoid—an "electrical spigot" that allowed one circuit to control another. By connecting two long telegraph wires, a solenoid served as a repeater, to reinvigorate a message weakened by the electrical resistance of the arriving wire and send it forward to the next repeater in the network. Solenoids in telegraph offices across the country also powered audible sounders that helped telegraphers hear incoming messages coded as dots and dashes.
This breakthrough was transformative. Meteorologists began exploiting the telegraph to build synchronous weather maps for forecasting, while geodesists separated by hundreds of miles synchronized astronomical observations to pin down precise longitudes. Electricity didn't stop at data; it revolutionized printing, turning wax engravings and photographic negatives into crisp press plates. By the late 1800s, electricity became a pillar of public safety, fostering municipal telegraph systems that wired fire-alarm and police call boxes directly to headquarters. By the mid-twentieth century, it had even refined the aesthetics of the map, producing the sharp, uniform labels we recognize today.
Innovation eventually moved into the hands of the public through the interactive orientation map. These "mall maps," featuring tiny bulbs triggered by pushbuttons, allowed tourists and shoppers to pinpoint their intended destinations at a touch. Long before the dawn of computer graphics, electricity was already the cartographer's silent partner—lighting drafting rooms, powering erasers, and illuminating the light tables used to reconcile maps of varying scales.
The book concludes by looking forward to the era of autonomous vehicles and intelligent highways. These represent "proactive prohibitive maps"—systems designed not just to show the world, but to actively regulate human movement. Ultimately, electrical innovation has done more than just power our tools; it has fundamentally rewired how we visualize and navigate our world.
The Book's Preface
Dictionaries offer diverse definitions of power, two of which are particularly relevant to making and using maps. One addresses military might and geopolitical influence, and a second focuses on electrical energy for lighting, heating, and running machinery. As a university professor who has taught and written about maps, I understand why scholars immersed in the societal impact of maps might favor the first definition, which addresses the map's roles in conquering territory, exploiting resources, and framing viewpoints. By contrast, educators and writers who focus on mapmaking tools and present-day applications no doubt appreciate the second definition, especially when expanded to encompass interactive maps, touch-sensitive flat screens, microprocessors, and geospatial technology in general.
In titling this book Electricity and Maps, I clearly appreciate the second definition. That said, few of these pages address digital computers, geographic databases, microelectronic circuits, and similar phenomena that account for much of the million-word encyclopedia the University of Chicago Press released in 2015 as the twentieth-century volume of its massive History of Cartography. As the encyclopedia's editor, I regret not devoting more of these million words to comparatively mundane devices like electrolytic batteries, button switches, and electromagnetic relays. A lapse I recognized a bit late.
To correct that oversight, I explore electricity's historical importance to making maps and making them work. Chapter One, titled "Electricity's Roles," lays out a basic argument for electricity's importance. I begin by comparing the electromagnetic relay to a spigot of sort—although a signal arriving at the relay from a distant source had been weakened by the electrical resistance of a long telegraph wire, this feeble signal was sufficiently strong for a coil connected to a local battery to send an identical signal forward to the next relay point. In addition to describing electricity's role in transmitting geographic observations over great distances, Chapter One explores the rise and consequences of the industrial production and distribution of electrical power, from the late nineteenth century onward. Another chapter examines how automatically boosted signals allowed an integrated network of weather stations to contribute to a national weather map, compiled two or three times a day, so that forecasters could identify and track storm centers. Other chapters address the use of electricity in making printing plates, measuring longitude, displaying locations on public orientation maps, transmitting fire alarms, facilitating cartographic drafting, and preventing collisions with low-clearance bridges.
To recap, my goal in writing this book is to recognize these older, non-micro roles of electric currents and magnetic impulses as the largely unsung heroes of modern cartography, still essential not only in making maps but also in making them work.