I do not know, if this information is interesting for you.
The areas where most of Wassmer come or came from is the so-called 'Hotzenwald' a part of the 'Schwarzwald' originated from small villages like Niedergebisbach or Obergebisbach.
During the 18th century have been a lot of fights/rebellion (keyword 'Salpeterer') between the people and the austrian Government (at that time this region today belonging to Germany and is close to the swiss border was called Vorderösterreich).
As naturally the rebellions failed and a lot of people left their home going maybe also to foreign countries. The same continued in the 19th century but here now based on the economical situation. Many people definitely left also to north america.
the origin of the Word Wassmer is by the way 'Wase' meaning a piece of grass or meadow and Wassmer therefore means something like 'meadow farmer', maybe orginally the name of a big farm. You also find similar names in Hotzenwald and the german speaking part of Switzerland like 'Wasmer', Wasner,Vasmer and so on.