apartment buildings now obscure both ends. (There’s a brief scene in Francis Ford Coppola’s brilliant 1974 film The Conversation where you can see Gene Hackman walking across the still-extant Western Pacific tracks near 15th Street; the plug at the tunnel’s north end is visible in the distance. Check out this amazing image on Flickr.)
What’s interesting to me is that long after the Western Pacific rails were torn up or paved over, the streets and buildings of Potrero Hill still follow their contours. And the longer you spend staring at maps, the more examples like this you find. At least in San Francisco, the urban landscape is like a palimpsest or a leathery skin, crisscrossed with scars that have healed but never quite disappeared.
At first I wondered whether the tilted clubhouse on Third Street might have grown up atop some other abandoned rail line. But there aren’t any traces of such a line on adjacent blocks. I asked a few people in the neighborhood about the oddity, but no one seemed to know the story.
And that’s where my puzzle stood, until one evening a month or two ago when I was browsing Google’s Lat Long Blog and found a guest article by my friend David Rumsey, one of the country’s leading collectors of historical maps. I’ve known David since 2005, when I wrote a short feature about him for Technology Review. His blog post was about an amazing set of high-resolution aerial images of San Francisco, captured in 1938 by aerial photographer Harrison Ryker. The 164 prints in the collection cover the entire city at 1-meter resolution—higher than most satellite surveys even today. Rumsey’s team had just finished digitizing, cataloguing, and “geo-referencing” the prints—that is, matching control points on the ground with objects of known latitudes and longitude, so that the digital versions of the photos could be assembled into an accurate mosaic and displayed inside GIS software such as Google Earth.
In fact, in the blog post Rumsey informed readers that the 1938 imagery had just been added to historical imagery layers of Google Earth. I immediately thought of my Third Street buildings. I fired up Google Earth on my Mac, turned on the Rumsey Historical Maps layer, navigated to my neighborhood, and set the time slider back to 1938. Here’s what I found:
From this astonishing photograph, it appears that there was some sort of industrial compound covering the entire area bounded by Iowa Street, Third Street, 22nd Street, and 23rd Street. The dominant feature was a long building that sliced across what are now four city blocks, at the same angle as the current-day Hells Angels Clubhouse. In fact the clubhouse is visible in the 1938 image, just to the north of the tilted lot, on the Third Street end.
This was a major step forward. But I still had no idea what the structure was; there was no convenient label on the
