Main street is not the, or even a, main street. It used to be a main street, but in the 1980s there was a push to make the downtown business area bigger and Downtown Plaza was created and improved from an older street, a block over. That and the small, but never fully used, mall pretty much killed Main street.
North North avenue. Downtown Plaza was made from part of North North avenue. North of Downtown Plaza, it becomes North North again. South of an east-west Avenue it used to be South North avenue, but that name was changed a while ago.
The avenue dividing North and South is Blue Earth Avenue. Blue Earth is the next town of any size to the east. Blue Earth avenue, named for another town (or county, or river, none of which are all that near Fairmont) is the main east-west street in Fairmont.