To Ken Burns, of ccourse, the producer of "The Civil War" (1990) and many others, including one of his best: "Mark Twain". To own the sound tracks of these productions is to be blessed.
I loved "Ashokan Farewell" (by Jay Unger) from "The Civil War". See link below.
The second haunting tune is on "Mark Twain". "How Can I Keep from Singing" is an old gospel song. and is beautifully played by Jacqueline Schwab. The words are nice, also.
On the "Mark Twain" soundtrack, you will also like "Sweet Betsy from Pike" and "Hard Times".
I'd like to mention David McCullough, the unsurpassed narrator of "The Civil War" production - a voice of sincerity.
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"Ashokan Farewell", with Lincoln slide show:
http://www.youtube.com/watch?v=UGqBggXvtDE