Via Perfect Duluth Day, here’s a map showing an early railroad connection from Duluth to the northwest, all the way to Winnipeg. This was right in the middle of the era when both cities were booming.
Here’s the map, which also shows early railroad era connections from Duluth into Wisconsin:
And an expandable close-up of northern Minnesota:
Interestingly to me, the early railroad line charts roughly the same path as the original “Line 3” route, through the Leech Lake and to the south of Red Lake, on its way to the northwest corner of Minnesota.