The Vanport Flood: it happened 74 years ago today

Published: May. 30, 2022 at 6:13 PM PDT
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74 years ago today, what was once Oregon’s 2nd largest city was erased from the map in hours. If you’ve never heard of the Vanport Flood, read on…it only happened 5 miles from downtown Portland.

I love weather AND history, so I find this flood fascinating, especially since it’s results echo through Portland even in 2022.

I’ll be brief, since it’s a long story.

During World War II (1940-45), huge numbers of workers were brought in to work in the shipyards here in Portland. There was an urgent need for housing, so a city was quickly built and called VANPORT (Vancouver+Portland) on the flats north of Portland. That’s the low area west of I-5 around Delta Park where PIR, Heron Lakes, and Delta Park West is now.


That city contained 40,000 at it’s peak, making it the 2nd largest city in the state!

Vanport(Portland National Weather Service)

After the war, lots of folks moved away, but there were still around 13,000+ residents there by the Spring of 1948, three years after the war ended. Even a college had opened in the city for the returning GI’s…the Vanport College.


The winter of 1947-48 brought massive snowfall to the mountains of the Pacific Northwest and Rockies, along with lots of rain. At this time there were very few dams to hold back spring floods on the Columbia and Snake Rivers…although Grand Coulee and Bonneville Dam both were operational. The Columbia River rose throughout May 1948 and by Memorial Day Weekend was approaching the 30′ level on the Vancouver gauge. That’s within 4′ of the all-time high in 1894. For comparison, that 1948 level is about 14′ higher than the river is right now! I notice the Portland Housing Authority had put out a notice in the week before saying “REMEMBER: DIKES ARE SAFE AT PRESENT. YOU WILL BE WARNED IF NECESSARY. YOU WILL HAVE TIME TO LEAVE. DON’T GET EXCITED.”

That didn’t happen. On Memorial Day, May 30th, (used to be on that date instead of the last Monday of May) the railroad dike on the west side of the city (where the railroad is now) burst around 4:20pm. A 10 foot wall of water went surging into the city. By sunset the city was inundated and remained so for over a month. A few factors helped keep the death toll quite low (just 15): it was the holiday weekend with lots of people out of town and mild temps plus bright daylight kept confusion to a minimum too I suppose. Here’s the view two weeks later from just about the same vantage point. Note the triangular are of trees on the edge of the slough in both before/after pictures:

Vanport June 15, 1948
Vanport June 15, 1948(Portland National Weather Service)

Interesting to note that the river kept rising, and peaked about the date this picture was taken…at exactly 31′ on the Vancouver gauge. The flood was the 2nd highest on the Columbia River since record keeping began in the 1800s.

The result?

1. About 1/3 of the residents were African-American; largely settling into north and northeast Portland following the flood. My grandparents on one side of the family were raised in and lived in that area from the 1910s to 1950s. I remember them talking about the changes after WWII. You can find lots of good information about this online which is way beyond the scope of a weather blog. Interesting, especially considering demographic changes in the area (once again) the past 30 years.

2. Vanport College was called “the college that wouldn’t die”, restarted in downtown Portland, and became Portland State University.

3. The town wasn’t rebuilt, but became a raceway, a park, a golf course, and wetlands.

4. The Flood Control Act of 1950 spurred a massive program of dam building along the Columbia and its tributaries — due to the 1948 flood.


Chief Meteorologist Mark Nelsen