> On I-5 near Woodburn, OR

The section of I-5 between Portland and Salem is absolutely psychotic, and I have never been able to reason out exactly why. It consistently has a left lane jammed with angry people going at or below the speed limit, a fairly normal center lane filled with cruisers, and a mostly empty right lane with the occasional big rig and regular very-high-speed cars expressing their frustration with the left lane by going 25+ mph over the limit in the right lane.

I know that's what you basically just said. Just venting. The driver behavior in that section of freeway confounds me, and I do not know what the underlying cause is. It is otherwise an unremarkable bit of interstate like any other.

Truckers sometimes have a good reason to do that -- they can't brake or accelerate as quickly as a small vehicle, and thus can end up going very slowly if they stick with the right lane. To a driver going 3 exits down the 205 it's not a big deal, to a truck driver doing the same they may be at the end of a long haul up the I5 and every minute starts to count since it can affect their pay. And if you can avoid hard braking/hard acceleration in the right lane, that can help your fuel costs quite a bit since slowly coasting behind someone doing 5 under in the left lane is more efficient than jerking around in the right lane.

There are plenty of ramps on I5 and 205 that I merge to the left for because I know they will spill into the right and (when it exists) middle lanes. Because of how traffic also reacts to brake lights (some people brake too hard even when they have sufficient distance to let off the gas and coast to a slower speed) it seems like it ends up making my experience through those stretches a bit better.

Ultimately, any individual behaviour is largely irrelevant, it's what the whole mass of cars moving along does that affects things the most. Often you don't want to be the (significantly) odd one out regardless of the situation.

It's not the fastest often because it's oversubscribed and people do not understand that the car has a 3rd, mostly underuntilized, state of neither pedal depressed (ie "coasting") ... so they create cascading braking pileups ...