An interesting map showing the date of construction of buildings within the Portland city limits. Red indicates the oldest buildings, built before 1910. It would be interesting to see new construction since 1990, when this map was produced.
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8 Responses to “Building Construction Date Map, 1990”
I’m guessing this data comes from the Multnomah County property tax records, which track when buildings are constructed. Buildings that were torn down and replaced would no longer appear in the dataset, so it seems like it would be difficult to track buildings that have been lost. But maybe you could get at building losses by tracking the number of lot divisions, demolition permits, or other data that would indicate a change to the structures on a tax lot. It would be pretty painstaking, though.
Yes, stiefve is right, as far as the data I’ve been able to find, it’s from property tax records. It’s in theory possible to come up with a such an overlay, but I think too much data loss or errors would creep in with the method suggested. Maybe someday when I have time I’ll try!
Actually, it’s not that hard to get snapshot data from different points in the past, and use those to generate the data – at least for stuff that’s been recorded on computers.
Examples of this have been done. The Atlas of Oregon has several maps showing building change over time in the downtown area. I suspect much of that data comes from Sanborn maps.
There have been various efforts to digitize Sanborn maps from different places around the country, but I don’t know of the current state of any of that in the Portland area. It wouldn’t be cheap to do so, so there’s probably not enough need for such things to justify the expense.
Now, that being said, it does seem that the city has spent a fair amount of effort digitizing the historical building (and presumably demolition) permits, but I don’t know the state of that data.
Also, ask and ye shall receive. Here’s a quick and dirty (emphasis on the dirty) map of properties built in Portland since 1990, inclusive. It’s based on Metro’s May 2012 RLIS data set.
It’s a PDF (9MB) and you should be able to zoom in and see a good bit of detail. If I get really ambitious, it wouldn’t be too hard to throw this up as a browsable web map, but hey, I’m doing this while I’m work, so don’t ask too much.
Thanks, GeoGeek! That’s a useful map. Lots of building happening in Alberta/Vernon and Outer Southeast, which seems consistent with anecdotal and media stories about gentrification and population growth outside of downtown and inner-ring neighborhoods in the last 15-20 years (with the exception of the Pear, of course).
A bit off-topic, but I’d love to see something like the Manahatta project (http://welikia.org/) done for Portland.