I agree with others about the minimizing of german culture in american pop culture because of the world wars, but I think another problem German's have with distinguishing their immigration history is their architecture. There aren't really that many examples of historic traditional big city German architecture in the US. Germantown, Philadelphia during colonial times was effectively a large town and this is what the buildings generally looked like:
https://www.google.com/maps/@40.0341...7i16384!8i8192
Germans were real influential in defining the American small town and farm aesthetic.