“A good science fiction story should be able to predict not the automobile but the traffic jam”*…
Ward Shelley‘s map of “The History of Science Fiction”– click here for a zoomable version.
This map plots the science fiction literary genre from its nascent roots in mythology and fantastic stories to the somewhat calcified post-Star Wars space opera epics of today. Rather than a narrative emerging out of the data, here the narrative structure precedes and organizes the data: the movement of years is from left to right across the grid that represents time, distorted and reconfigured into the form of a bug-eyed monster whose tentacles are like trace roots to pre-historical sources and whose body is the corpus of sci-fi literature. Science fiction is seen as the offspring of the collision of the Enlightenment (providing science) and Romanticism, which birthed gothic fiction, source not only of sci-fi, but also of crime novels, horror, westerns, and fantasy (all of which can be seen exiting through wormholes to their own diagrams, elsewhere). Science fiction progressed through a number of distinct periods, which are charted, citing hundreds of the most important works and authors, and which includes film and television as well…
More at Places and Spaces‘ “History of Science Fiction.”
* Frederik Pohl
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As we reach for our ray guns, we might recall that it was on this date in 1869 that the first U.S. Transcontinental Railway was ceremonially completed with the driving of the “Golden Spike.” Known as the “Pacific Railroad” when it opened, it served as a vital channel for trade, commerce, and travel– for the first time, shipping and commerce could thrive away from navigable waterways– and it opened vast regions of the North American heartland for settlement.
(In fact, while not “transcontinental” in the same sense, the first railroad to connect two oceans directly, the Panama Rail Road, opened in 1855, when a locomotive made the first trek from the Atlantic to the Pacific.)

At the ceremony for the driving of the “Golden Spike” at Promontory Summit, Utah, May 10, 1869