By 1919, the forests were gone that had fed the mills of Minneapolis. 
"Remaining 5 percent after the balance of timber is removed and brush burned, Section 15, Township 145N, Range 30W", Minnesota National Forest Reserve, 1904. 
Minnesota Historical Society Photograph Collection, Location: Collection I.11.23

By 1919, no loggable white pine remained in the Mississippi River basin. The Northland mill was the last in Minneapolis to shut its doors. Over 80 years, the power of the falls had cut many billions of feet of lumber from the pine forests. As the mills became bigger and faster, more and more trees were cut. Giant forest fires wiped out others. When the trees were all gone, the sawmills died. Thousands of people lost their jobs in the mills and also in companies that made furniture, crates, or other products from the lumber.

Why Was All the Pine Logged?

For more information, see Agnes Larson, History of the White Pine Industry in Minnesota, (Minneapolis: University of Minnesota Press, 1949)