I saw this article at BoingBoing, and had to look it up.
From Wikipedia:
The Aroma of Tacoma, also known as the Tacoma Aroma, is a putrid and unpleasant odor associated with Tacoma, Washington, United States.[1] The smell has been described as similar to the odor of rotten eggs.[2] The odor is not noticeable throughout the city, but is rather concentrated in the Tacoma tideflats and is frequently smelled by motorists traveling that section of Interstate 5.[2]
It’s not a problem really anymore. There’s lots of fun things to do in Tacoma if you find yourself in the area. I’m not super familiar, just been through a few times
As another commenter said, it’s due to paper mills which use sulphur compounds to turn wood into pulp and those are still common elsewhere in the state
Yep, the paper mills have long closed down in that area!