While Lindell Library should be your first step, here are additional places in the Twin Cities for local research. You can schedule a research appointment at each one, but note that you will need to visit in person!
These open-source databases of full-text newspapers are a rich source of information on American history.
The Minnesota Historical Society has created online excellent descriptions of their collections and in some instances digitized an entire collection. This page contains links to those descriptions and collections. This is just a sampling of what is available at the Society!