As Gardner Dozois, in his introduction to this short story in The Best of the Best : 20 Years of the Year's Best Science Fiction, puts it "There are many tragic periods in history. As the melancholy story that follows suggests, though, there are few of those periods that couldn't also have been made a little worse (his emphasis)"(293).
That quote pretty much sums up "The Lincoln Train," which asks "How would the American Civil War have ended if Lincoln had been shot but hadn't died." McHugh's answer is "pretty bleak." The North still wins the war, true, but, in the aftermath, due to reasons that I, as someone that has never studied American History, can't understand, certain parties take power and start a horrific forced resettlement of all Southerners that still had slaves at the end of the war, much like how the Americans "resettled" many Native tribes. The results are similarly as bleak.
From the point of view of a character study, this is a very engaging story. The main character, a young woman named Clara, is very sympathetic, and her plight as one of the "recalcitrant" Southerners, is engaging. I've never really been a fan of alternate history. I don't usually see the point other than as an academic exercise. However, McHugh has definitely pulled an interesting story out of this particular "what if."
Okay, that's all I have time for now. Two more to go before I'm caught up. I'll post those tonight.