Infiltration.org- Infiltration.org is another good resource that has been around since the very early 2000s. The websites founder passed away in 2005 and this it no longer is updated, rather only maintained. it is not a MN only website.
uer.ca- urban explorers resource is a forum that requires a account to explore properly. It has been around since the early 2000s and is one of the only forums of that time to still be maintained and is still active. Some stuff is behind a rank wall but a lot of interesting information may still be found. Its not an MN only resource.
Wayback Machine- Wayback Machine is a web archiving website where anyone without an account can archive/save a website as it is at the time of saving, this means that anyone can look at what a website looked like in the past. This is useful because many urban exploration websites that once existed were either no longer funded or under companies that disolved and thus so did the websites. This allows us to look at those no longer existing websites and we can pull information from them.
tcur.org- Twin Cities Urban Recon was a website that seems to have early origin from 2008, it is a sort of forum where people post about certain locations. But this website is no longer around and can only be viewed through Wayback machine, if you do, skip around through the years then more locations will appear on the front page that may not in other years.
r/MinnesotaUrbex- This subreddit has been around for a long while, people will post many pictures but gatekeep any locations out of fear of people flocking to them. If the picture is clear you could maybe pick it apart and possibly find a location that way but you have to be very persistent, occasionally you may find a comment as to a hint of what it could be and this may help that way too. This is useful but not dependable.