For the rest of you who are either not American or also have no plans over the holiday ;)
So, it's the 1870s. And for those of you who have gone and looked at the link that was posted a couple weeks ago, I suggest also looking at the info on the 1860s as it took a lot longer back then for things like books to disseminate.
I'm thinking it's early to mid 1870s. The Civil War has been over for less than 10 years, the South is an enormous mess, Reconstruction is rewriting slavery into Jim Crow. Lincoln's dead, Andrew Johnson was wildly unpopular, Grant is now President. The nation is just barely starting to heal from the previous 20 years of internal strife.
The transcontinental railroad was completed in 1869. The telegraph already existed by 1870, but the railroad extended the reach of the telegraph system. The telephone is introduced during the 1870s.
I'm also thinking that in this AU, Elizabeth would be younger than she is in canon. Not by much, but maybe in her early 30s as opposed to mid/late 30s. That would put her birth date around 1840. If we're assuming she came from a well-to-do background, and not from the south, she would've been a young girl when the Seneca Falls convention happened in 1848. The suffrage movement, the abolition movement and later on the temperance movement were the three major social catalysts at work in her life.
What I'm getting at here is a simple question: do you think our AU Elizabeth is a virgin?
On the one hand, the societal norm of the era was that women were virgins until they married, and this would've been even more enforced with women from higher social classes. Elizabeth, being well-educated and from a good family would have kept her reputation fairly clean. The "real" Elizabeth seems to have certain notions about right and wrong, although she's not presented as deeply religious, she does have a moral code that means something to her.
On the other hand, we have a ridiculously oversimplified notion of sexuality in our own times, much less our understanding of sex in the past. There's a bizarre assumption in some quarters that nobody had sex outside of marriage until the 1960s, which is flat out wrong. Like the human (female) body wasn't capable of feeling pleasure until recently. Like women, even without Susie Bright and that Canadian doctor with the call-in show didn't know "if you touch there it'll feel good" just by their own discoveries, like they didn't have sex drives because it was the Victorian era *eyeroll*.
Still, 150 years ago, marriage was still in a lot of cases about economics. Women married hopefully for love but mostly for survival. Also at that time, women had no legal status in many states. The battle was on to overturn laws that said a husband automatically owned both his wife's body and possessions (any income she earned was legally his money) but it wasn't finished at the time.
Also, you have the war. Traditionally wars (real ones, anyway) have a tendency to upend social conventions. Established gender roles and social norms get thrown out the window when armageddon is over the hills. A lot of things that seemed vitally important customs no longer seem so pressing ("Gone With The Wind" was on cable last night - there's some moments in there that show how irrelevant certain prejudices and niceties became during the war).
If Elizabeth was engaged to Simon, and the war arrived, there's every possibility that she would "give herself" to him or give in to their feelings in the heat of the moment (especially if they weren't getting married yet but there was a risk they would never see each other again). Or at least I could see that argument being made. Though that assumes that Simon would have served in the army or gone to work as a doctor with the army.
All this is speculative, of course, and a lot would depend on what people are thinking in regards to Elizabeth and how she ended up a store proprietor in a rural town in the West. With the railroad open, getting there wouldn't have been too difficult. Why she is there is another story. What happened to cause her not to marry Simon is also a factor.
And probably whether you're wanting fic that involves gunslinger!John deflowering his love, or fic that involves her afraid to confess to him that she's not a virgin any more. ;)