Wow! This is impressive. They explain is thusly:
“Michigan Beer Cans (MBC)” is an attempt to show pictorially all known variations of beer cans produced from our home state, providing a useful, evolving index to aid the Michigan specialist. To that end, we have included all variations, some obvious, some obscure, even down to different canning companies producing cans of the same label for the same brewery. As long as there is a distinguishable difference between the face(s) or text of two cans of beer, we have included them as variations. While this level of detail makes it unlikely our reference will ever be complete, it also makes it much more likely we will have plenty of opportunity to continue our pursuit!!!