Yodelling originated in the Alpine regions of Europe - not just Switzerland - and is still performed by many artistes there today. The styles vary from region to region - generally the slow, beautiful accurate yodels are sung by the Swiss whilst the faster more spectacular yodels are found more in Bavaria in Germany. A good example of Swiss yodels is Vreni Kneubuhl, whilst Franzl Lang is the most lauded master from Munich. Peter Hinnen is a Swiss who unusually perfected speed yodelling and went on to record pop and country music with a yodel.
Travelling European families in the 1800s and early 20th century were often heard on travelling "medicine" shows in the US and it seams likely that that waswhere Jimmie Rodgers learned it. Rodgers was a black-face minstrel after leaving the railroad. Some say he learned the art from Goebel Reeves but I understand that by the time the two met, Rodgers was already yodelling.
Whilst Rodgers' yodelling was simple - he had few competitors - he influenced and inspiured many including Elton Britt and gene autry (but not Wilf "Montana Slim" Carter, who was inspired by a minstrel yodeller calling himself the "Yodelling Fool"). Rodgers yodel was crisp and clear and he was indeed a fine yodeller. Others, like Britt, took his exampoles and developed the art further.
Meanwhile in australia and new Zealand, the records of Rodgers, Gene autry and the English music hall yodeller Harry Torrani were being released and inspired thousands of kids to try to yodel. Top of the pops there was Tex Morton (Robert Lane) who inspired a whole new country music industry that still thrives today.
In England we had George van dusen, Torrani, Bert Terrell and ronnie Ronalde amongst others (Ronalde is probably also the best whistler the world has ver known). Belgium had Bobbejaan schoiepen (pronounved Bobby yarn skoopen), Holland had several yodellers including Jodel jerry, Olga Lowina and texas Kitty prins, South Africa had Charles Jacobie and Santa vorster, etc - most will testify to having been influenced by Jimmie Rodgers, Wilf carter, elton Britt or Slim Whitman.
Frank Ifield was one of the many inspired by the early scene in australia and he himself inspired many more through the years - there, in the UK and elsewhere. Mary Schneider (classically trained but probably the best yodeller in the English speaking world today) started as a hillbilly singer on Regal Zonophone 78s in the 50s but herself is idol to many youngsters today.
Perhaps most spectacular of yodel careers has been that of Slim Whitman. Virtually ignored in his homoe country of USA for years, he has sold over a hundred million records, recorded more that 50 albums, broken box office records across the world for more than 5 decades and has one of the most beautiful singing voices in country music. More people should listen before they mock - the guy's voice is amazing.
In recent years I have worked with several labels to make more yodel material available. Seek out "The Greatest Yodelling Album Of All Time" a 2CD set on the Australian Rajon label - it has 50 yodellers from around the world. Try also the UK-based Jasmine label (look them up on www.jasmine-records.co.uk)- we have done albums on Whitman, Ifield, a tribute to Jimmie Rodgers, a 4CD set of singing cowboys, 2 CDs of Britt, one of Slim Clark and three CDs dedicated to country yodelling. There is also a CD of Frank Ifield's pre-pop Australian years with loads of yodels! I am not an employee - I just compile albums for them.
Hope this helps albeit a bit late (just stumbled on the blog). Contact me on paul@pithon.co.uk if you want to know more.