In the PNW we commonly use porous asphalt (so the rain doesn't build up and cause hydroplaning) as well. A few interstates still use concrete. I wouldn't be s

In the PNW we commonly use porous asphalt (so the rain doesn't build up and cause hydroplaning) as well. A few interstates still use concrete. I wouldn't be surprised if that had something to do with weather and related maintenance requirements. I-90 being a pretty good example.