The melody of "Streets of Laredo" is said to have derived from "The Bard of Armagh" an old Irish tune. Here's a nice version of this by Tommy Makem:
See if you can hear the similarity.
William Congreve (1670-1729) said that music hath charm to soothe the savage breast. I found from experience that some of these melodies could also soothe a nasty flare-up of colitis.