What is this abandoned airport between Montague and Rothbury, Michigan?
The airport is Ottiger Airport (2MI6) which is closed indefinitely. I cannot find any information on when it was closed or for what reason. The last update date that I can find for the charts is August of 2006, which is probably when the airport was closed.

Apparently there is one person who is trying to revive the airport for private use according to this post on Facebook.