Today, I’ve added brand-new 159-year-old imagery to Pastmapper. Now, in addition to San Francisco, check out… San Matheo! That’s not a typo; San Matheo is (or would become) the San Mateo of today. In 2012, it’s a city about 20 miles south of San Francisco, home to 700,000 people, pharma, biotech and high-tech firms, and the location of the Thunderbolt Motel murder scene in the Steve McQueen classic movie Bullitt. The spelling didn’t standardize to San Mateo until the late 1850s, and the area didn’t become a proper city until 1863, when the San Francisco-San Jose railroad passed through the area. The earliest English language reference to San Matheo that I could find was from British naval Captain Frederick William Beechey, who wrote about it in 1831.

With railroads still a decade in the future, 1853 San Matheo didn’t have much in the way of settlement. The astonishing thing about this rural area is the winding path of wetland tributaries, yet unbridled by the human development that would soon transform the shape of the San Francisco Bay. We’ll see in future iterations of the Pastmap that this early coastline would be forged into something very different in subsequent years. The space that would become Foster City, for example, began as nothing more than meandering streams and wetlands.

The San Matheo map imagery comes from the US Coast Survey’s T-433 map, originally surveyed in 1853, just a few months after the San Francisco map. Fortunately for me, and unlike the 1853 San Francisco coastline project, this map didn’t require manual tracing of scanned lines, because it had already been made available in vector form, thanks to the incredible digital assets from the San Francisco Estuary Institute. More on this great project, and how they’ll enable incredibly high quality historical map data, will be coming soon.


Flip back and forth between today’s map at the 1853 map though, and you’ll see that this first iteration of the 1853 San Matheo map has a problem. Like me, you may wonder, why isn’t El Camino Real in the same place as today? 

When I first saw this discrepancy, I was tempted simply to move the line for El Camino Real, to make it line up nice and cleanly with today’s alignment of Highway 82. But would that be historically accurate?

To find out, I’ve consulted additional maps of the region, and have aligned them over the specific area in question to investigate the highway’s evolution. The US Coast Survey produced a map in 1899 (surveyed in 1892) and another in 1915 (surveyed in 1914), and El Camino Real is clearly shown on both of them. My logic here: if the alignment of El Camino Real in these maps matches this questionable 1853 alignment, then I can confidently render it as shown. However, if 1892 and 1914 match the present-day, I’m left with two possible conclusions; either (1) The 1853 map is wrong, or (2) The highway was moved at some point between 1853 and 1892.

Here’s how things line up between 1853, 1892, and 1914:

Strangely, nothing seems to line up perfectly. 1892 and 1914 match each other, and don’t match 1853, but the modern alignment doesn’t line up perfectly to either one. It seems more likely that the alignment might have changed in the 19th century than during the 20th, but I simply don’t have enough data yet. So my conclusion is that I still don’t know. For the time being, I’ll be leaving the alignment as rendered in the 1853 survey map. Pending further data confirmation, I suspect the Pastmapper version will change.

Creating a comprehensive set of maps of the past requires dealing with a wide variety of source materials. Some of these maps were the products of fastidious surveying, and were conducted with the utmost attention to geospatial accuracy and detail. Others were not. And most frustratingly of all, some maps may contain human mistakes, intentional biases, or errors due to older surveying methods. This highway alignment question is likely the first of many more complex issues that I’ll be tackling as the project continues.


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1 Comment » for The Bumpy Road to Mapping San Matheo
  1. John Ridener says:

    Check the projection/spatial reference information on each of your charts. If your charts use different datums, etc., that can account for the offset.