Montana has a speed limit of 75 now from what I understand. They got tired of their highways being used as speed test tracks. I don't know how hard they enforce there though. The speed limit here in Colorado is 75 once you are out of town. I never go more than 4 over while in Colorado and have yet to receive a ticket here.

Most of the states out west here have a speed limit of 75 (and 80 in some places in Utah and Texas). California is still 65, but I try to avoid driving in that state as much as possible.