The Old West- where you couldn't throw a rock without hitting somebody singin' a song about hittin' the trail, workin' hard, or that ol' gal I left behind me. This was the time of the Westward Expansion, the Transcontinental Railroad and COWBOYS DADBURNIT.
"Drill, Ye Tarriers, Drill", a railway song first published in 1888, and one of those folk tunes that changes lyrics and even melody depending on who's performing it, if these wildly different versions are any indication.
"I've Been Working on the Railroad", another railway song that any American should be able to conjure up (they ought to anyway), first published in 1894. The "kitchen" section is actually a different folk song that got absorbed into it later.
"Fireball Mail", written by Fred Rose under the pseudonym Floyd Jenkins, and first recorded by Roy Acuff in 1942.
"The Old Chisholm Trail", a cowboy song about a cattle-driving trail that went from Texas up to Kansas.
"Who Shot the Hole in My Sombrero?", written by Milton Leeds and Billy Hayes in 1949, a somewhat non-PC song originally sung in an exaggerated Mexican accent. In fact, the voice of the animatronic dog that sung it in the attraction was later changed to a Texan accent after complaints.
Unfortunately, this is the only version with lyrics I've found (you can probably guess why it's scarce), so you may want to read up on it here.
"Billy the Kid", a rather unsympathetic tune about the famed outlaw, first published in the 1910s I think. Unfortunately, I can't seem to find the song anywhere, so you'll have to make do with the lyrics: http://www.recmusic.org/lieder/get_text.html?TextId=54607&RF=0
"Home on the Range", another classic that everyone should know- you should know the first verse and chorus anyway- originally written as a poem by Dr. Brewster M. Higley in 1876, and set to music by his friend Daniel E. Kelly.
It keeps coming back to the Chipmunks doesn't it?
As you can see, the Imagineers didn't always get the time periods quite right, and many a more recent song wound up among authentic ones. Up next- the Gay '90s!