I’d also add it’s interesting you mention MD troops in a 2-to-1 ratio favoring Unionists.
Because that is about the ratio today (and all my life) of Dems outnumbering Repubs here (at least in registration).
On that two-to-one ratio you mentioned — the important point to remember is that most Americans were farmers in 1860, and most cities, even Baltimore, were relatively small.
Thus it should come as no surprise to learn that 1860 Maryland farmers with no slaves outnumbered those with slaves by a factor of several to one.
And sons of those farmers joined the Union Army by two to one over the Confederates.
Today’s economics are vastly different, with fewer that 5% of Americans farming, and still voting Republican, easily offset by great tracts of big cities filled with government housing for Democrat voters.
So it’s easy to see how Maryland’s two-to-one Unionists farmer - soldiers in 1860 were replaced by two-to-one big city Democrat voters today.