The panhandle of Idaho is geographically isolated from the rest of the state by lots of wilderness. Up there, they have a lot of activity with the cities on the Washington side of the border, like Spokane. It's a pain in the ass to change time zones everytime someone in Coeur D'Alene has to run over to Spokane to do some shopping.
And, indeed, as illustrated above there's an interstate link going from Coeur D'Alene into Washington, while the north-south road links aren't nearly as good. Thus, the northern bit of the state is more closely integrated with parts of Washington than with southern Idaho. You learn something new every day as a blogger.