* The L&N Railroad in the Civil War: A Vital North-South Link and the Struggle to Control It by Dan Lee (McFarland, 2011).
Given their importance (and the Louisville & Nashville certainly was critical to western theater logistics) as well as the more general interest in American railroads, it is a bit surprising there aren't more of these published. I've reviewed a couple other recent vintage line histories with significant Civil War content: here and here.
* One Continuous Fight: The Retreat from Gettysburg and the Pursuit of Lee's Army of Northern Virginia, July 4 - 14, 1863 by Eric Wittenberg, J. David Petruzzi, and Michael F. Nugent (Savas Beatie, 2011).
S-B is reprinting a number of titles this year, including many from Ironclad Publishing, and this is the first paperback edition of One Continuous Fight. I reviewed the hardcover back in '08 (link).