Documentation for the Long Prairie earthquake first appeared at the time of the 1917 Staples (Motley) event, and is based principally upon the testimony of an old settler, Hon. William E. Lee. Lee is referred to by Warren Upham (1917), archaeologist of the Minnesota Historical Society, as the "most prominent citizen of Long Prairie." Lee is quoted by the St. Paul Pioneer Press of 9 September 1917 as writing to Upham: "I lived at Long Prairie before the Civil War and we had an earthquake shock at that time. I was a small boy but remember it very distinctly; it was either in 1860 or 1861. It was the subject of general talk in this locality at the time and I have no doubt there are other old settlers who may recall it."

Lee is further quoted by the Long Prairie Leader of 6 September 1917 as saying with reference to the 1917 event that "the vicinity experienced a harder shock in 1860, one that would have done damage had the country been more thickly settled at that time."