I would bet on Yale Bowl

http://news.yale.edu/sites/default/files/imagecache/video_photo_main/YaleBowl2.jpg

99.9% sure this is Michigan University Stadium. My mobile is on the fritz so I cannot post the link I want too, but google Michigan Stadium 1919 and you will find very similar pic from 1927 after the stadium had been renovated. I would goto michigan.scout.com and post the pic there for verification. The shear size, tunnels, bowl shape, and horizon matches Michigan Stadium's unique characteristics. Edit- If you confirm this is UM Stadium at the website I provided alumni will find it and add to their collection with much joy.

There are a couple of questions that I have. Firstly, do you know that the photo is from 1919 or are you guessing? If it is from 1919 then it can not be Michigan as it was not built until 1927. It was actually the legendary Fielding Yost who spearheaded the project and recommended that the new 72,000 person stadium be modeled after the Yale Bowl.

Another reason that I suspect it is not Michigan Stadium is that your images show curves behind the end zone while Michigan Stadium has curved edges but flat sides. There also are not stairs leading down to the field like there is in your photo.

I believe that it is the Yale Bowl as well but I cannot confirm that. Looking at a modern image of the Yale Bowl, you can see the curves around the entire stadium as well as the stairs leading down to the field similar to your photos.

Sources: Michigan Stadium History: http://www.mgoblue.com/sports/m-footbl/spec-rel/062008aaa.html

First year of Michigan Stadium (1927): http://upload.wikimedia.org/wikipedia/commons/1/1b/Michigan_Stadium_opening_3c27311.png

Modern Image of the Yale Bowl: http://upload.wikimedia.org/wikipedia/commons/9/97/YaleBowl-Field1a.JPG