Portland is a well-studied city, when it comes to studies as to how contagious diseases spread. One thing we know is that social distancing works, and works far better at the beginning of an epidemic. That's confirmed by another study, and by fall-off in common flu cases after 9/11 and detailed statistically here.
It's probably reached Oregon now, with a Portland case awaiting final confirmation, now considered 'probable' by CDC guidelines.
Here's today's WSJ flu blog.