President Eisenhower's ancestor arrived in 1741 and the name was changed from Eisenhauer to Eisenhower. To identify things German we must be able to read the many clues which dot the American landscape. The Indianapolis Zoo's two reindeer are named Thor and Oden and the groundhogs have names such as Phil and Henrietta. The Kroger butchers appearing in the TV ads are called Alex and Max. The German-American on the Barney Miller show is named Dietrich.
Amish names are always German.
Very few people know how their ancestors got their names. Humans have always named. In order to understand the organically and historically grown world of family names, we need to go back to the time when family names began to appear. A name, first attached to the first bearer, became a family name and a part of the inheritance passed from father to children. This practice appeared at the time when it became the custom to enter family names into civil registers, tax registers, etc.