From their website...604-685-4311 is the number for the US Embassy in Vancouver. One page calls it the normal line, and another page calls it the emergency number.
However, they say emergency passports are only issued during normal business hours. And I can't be sure of it, but I think they would be taking the 4th off.

But you gotta try, right?
Not sure if this will help, but look on facebook for USConsulateVancouver. (I would have given the link but I think for other reasons it wouldn't have gone through)
So you haven't gone through customs, right? And they'll require a passport. So you're going to have to get help.
Because the WHTI says
"
What types of documents are accepted for entry into the United States via land and sea?
U.S. citizens can present a valid: U.S. Passport; Passport Card; Enhanced Driver’s License;
Trusted Traveler Program card (NEXUS, SENTRI or FAST)..."
So if you had, say, an enhanced DL, and you could somehow get through customs, it seems you could board the ship (b/c leaving Canada and going to Alaska on a ship is entering the US by sea). It's that customs part that's difficult.
Call that number. Get on FB.
I'm so sorry this happened. It can be so stressful getting off the plane and trying to make sure you have everything.
Also, call every number at the airline you can. If the person in your seat looks in that seatback pocket, they'll find it. We once found someone's driver's license, and WE were more stressed out about it than the FAs were. We had to insist that they call the gate agent and get that DL to the person. Hopefully someone sitting in your seat is just that stressed out, and will insist that the FAs do something. If that's happening, and you are insisting from your end, maybe it will make its way back.
If you look at flightaware at your flight, you can generally see the next flight your plane is taking, and so on.