In the mean time, I thought I'd make a real effort to get the divorce records, which I think are all public record. Alas, for my grandmother, I only have the most general idea of when and where the divorces might have occurred.
Her first marriage was in Manitoba, Canada. At the time, it seems a divorce could be gotten through the provincial courts or by Act of Parliament. I looked for the last name in the database for the statutory divorces and got nothing (which is mildly amazing). Then I tracked down where the boxes of court records went -- the Manitoba Archives -- found their researcher list, and sent e-mail questions out to a couple of the researchers to see if they want the job.
Her second marriage was very brief and in Spokane, so I sent an e-mail to the Spokane Superior Court clerk, mentioning the first divorce as well.
Her third marriage was longer, and in Whatcom County, so I sent an e-mail to the Whatcom County Superior Court clerk, mentioning all three divorces, but mostly the third.
I keep having to remind myself that there's a decent chance that none of these divorces exist. There was a lot of moving around, and _Putting Asunder_ makes utterly clear (in case that thing by Martin Luther slipped your mind) that moving and remarrying was a way to create the equivalent of a divorce.
Anyway. The other divorces I am more optimistic about. My great-grandfather was married four times, and the middle two predeceased him. I've got a very tight window for the first divorce, as the couple was still living together in the 1930 census, and he remarried in 1931. Even better, I have a Seattle Times newspaper listing the second divorced in the Granted column.
Washington State may actually provide the case files for me. Fingers crossed; I might learn something.
ETA: Altho I wonder what I'm going to do if I find out the Washington State dissolutions are actually annulments rather than divorces, due to the first marriage never being ended. That'd be something, right?