Or at least I’m fairly certainthat’s what it was. I’ve never seen one before, and certainly not here in Portland. We usually see these pretty boring white butterflies with some dots on them, not something as large and showy as this guy was. Sadly, I was too late to get a photo. Yeah, it’s mundane, but it cheered up an otherwise down day for me.
Eastern tiger swallowtails are probably our most common large butterfly. Followed by monarchs. Zebra swallowtails are my favorite though because you know pawpaws are around whenever you see them.
Not mundane at all, butterflies are gorgeous and uplifting. Here is a Tiger Swallowtail I snapped a photo of a few years ago in my driveway. I don’t know if it will appear full sized. It fills my screen:
The best butterflies I have seen so far this year are a couple of Black Swallowtails and a Red Admiral. Every few years I see a Zebra Swallowtail, one of my favorites. Once at summer camp I saw a Luna Moth and I can still recall how stunning it was.
Dennis
When I was living in NYC, I once shared about a half hour with a tiger swallowtail at the Brooklyn Botanic Garden. It was fluttering around a small lilac bush. I took lots of pics, which I have somewhere in slides.
Yay you! Love swallowtails, the meadows are full of them here (eastern version, and also zebras).
I saw my first Luna Moth last week, on the jamb of my window. Wow.
When I was a child my favorite butterfly was the Mourning Cloak. Haven’t seen one in decades.
They don’t have those in Portland?
Huh! I thought they were pretty much everywhere. Not the most common butterfly in Idaho, but I see them most places I go.
I don’t know about tiger swallowtails but the swallowtails over here are a menace to my lemon trees. I will not harm the butterflies but I also will not let their spawn devour my lovely trees. They are my mortal enemies. 
They are apparently common here, but I hadn’t seen any in our yard before. We’ve planted a lot of bee/butterfly friendly stuff, so hopefully will see more of them.