I tend to agree with all of the above posts. I was very intrigued by these photos as the photographer had been on the sidelines before, and obviously knew how to capture a game. My first impression was this was not an amateur, and a person very familiar with American football.

Here's what I've found with just some cursory examination; "Linstedt and Zimmerman; Coblenz am Rhine, Kalsein-Augusta-Ring Nr. 3". American photographer Francis John Dyer (1864-1924) was associated with "Linstedt and Zimmerman", and seems to have made quite a few postcards connected to the German printers.

Francis John Dyer was in Europe during World War I as many of his photos are of the subject. Not sure how long, or if he stayed after the war, but I agree with a lot of the assessments above that it is post WW1-1924. There is another Christmas tree photo from Lindstedt and Zimmerman ca. 1922 that is the first image on a search for the name. Below is the link to the Francis John Dyer collection at UC Berkeley. They may even be able to confirm it.

In the link it indicates Francis John Dyer was a US consul correspondent (March 1915-?), Dyer was in Swansea, Wales, later Tegucigalpa, Honduras, Nogales Mexico, and finally "Coblentz, Germany". Hope this was helpful, happy collecting!

http://www.oac.cdlib.org/findaid/ark...c/entire_text/