Before the maps
Linking the sky to places is one of astrology's oldest habits. Ptolemy's Tetrabiblos, written in the second century, assigned the regions of the known world to the signs of the zodiac, and for centuries an eclipse was read as bearing on the lands where it could be seen. In the early twentieth century two astrologers gave places degrees of their own. The British astrologer Sepharial set out geodetic equivalents in the 1920s, laying the zodiac round the Earth from the Greenwich meridian, and the Canadian astrologer Edward Johndro published The Earth in the Heavens, on the ruling degrees of cities, in 1929. The guide to geodetic astrology explains their system, which is still in use.
The first maps
The step from degrees to lines came in the middle of the century. Astrologers such as Charles Jayne, Donald Bradley, Steve Cozzi and Martin Jay Davis worked on ways to show where a chart's planets fell across the globe, and in 1966 Gary Duncan published the first computer-generated Astro Locality Map. The idea at their heart is the one every astrocartography map still draws: at any moment each planet is rising somewhere on Earth, setting somewhere else, overhead along one meridian and underfoot along the opposite one, and those places can be traced as lines.
Jim Lewis and Astro*Carto*Graphy
Jim Lewis, born James Lewis Slayden in Yonkers, New York, on June 5, 1941, made the idea popular. From 1976 he sold hand-drawn maps by mail with booklets explaining each line, under the name Astro*Carto*Graphy, and full-page advertisements for them appeared in astrology magazines. He lectured, wrote and taught his method widely, so that by the time his first book appeared chart services around the world were offering similar maps, and astrology software for personal computers was adding mapping modules. In 1982 he completed Cyclo*Carto*Graphy, which puts the transiting outer planets and the progressed inner planets on the same kind of map. He died in San Francisco on February 21, 1995. The Psychology of Astro*Carto*Graphy, written with Kenneth Irving, was published two years later.
The branches that grew beside it
Other locational techniques grew up in the same years. Michael Erlewine developed local space in the early 1970s, drawing each planet's compass direction from a birthplace as a line round the world, and Steve Cozzi's writing made it widely known; the local space chart draws it. Parans, the latitudes where two planets are angular at the same moment, draw on the old idea of stars that rise and set together. Lewis's own Cyclo*Carto*Graphy added time to the map, which this site's transit lines follow for transits.
Astrocartography today
What began as hand-drawn maps sent by post is now a map anyone can make in a browser in seconds. Astro*Carto*Graphy was Lewis's own name; astrocartography has become the common name for the technique, whoever draws the map. The method itself has barely changed: the lines are the same four for each planet that Lewis drew, now computed from precise ephemerides and time-zone databases instead of tables. What has changed is how much can be added around them, from city rankings to transits. The free astrocartography chart on this site draws every line for thirteen planets and points, and the guide to reading your map explains what astrologers read in each. Like everything in astrology, it remains a tradition rather than a measurement.