Washington State ML seasons start before the modern rifle seasons, which is how it should be. Then there is also a late season(s) after modern rifle. They are actually quite generous.
There is no traditional season, just ML. But no jacketed slugs or glass sights. Saboted lead slugs are allowed. I think shotgun primer ignition is allowed, but I'm not positive.
I'd like to see them divide the ML season into traditional/ML, first half of season traditional and second half any ML. IMHO, I think most inlines are just used as a way to take advantage of the ML seasons, and not for the love of muzzle loading.
One good thing here is that you can only buy your tag, be it deer or elk, as a ML tag or modern firearm tag. In other words, if you choose a ML deer tag, you'll only be hunting deer during the ML seasons, and with a ML. I usually get a modern firearm deer tag, and a ML elk tag. This year I didn't hunt deer, and next year if I do I'll probably go ML.
Still, ML season being first, that still attracts or encourages people to get the most whizz-bang, modern high tech inline they can so they can get out before the modern firearm hunters, but still have every advantage (as they percieve it) they can get.
Season before last, every last-man hunter I came across (about seven) during season had inlines, including the guy I hunt with. This last season, I saw three inlines, (not including my partner) and three Hawken type side hammer/percussion rifles. Me, myself and I are still the only flintlock shooters I've ever seen in the woods so far.