Vanport Flood

The Vanport Flood washed away Vanport City, the largest public housing
project ever built in the United States, at 4:05 p.m. on May 30, 1948, when
the dike holding back the Columbia River gave way. The city, at one time
responsible for housing nearly 50,000 people after construction was completed
in 1943, was underwater by nightfall. Fifteen people died in the flood. The Vanport flood had a huge affect on the African American community in Portland and has been compared to that of Katrina.

Click this link for a list of resources (photos, oral histories, books, etc) about the Vanport flood.
http://www.opb.org/programs/oregonterritory/episodes/2005/0916/index.php