It is my assessment that the Vikings did not penetrate deep into the heart of the Midwest. On the basis of my own intuition, I do not see the reason why a seafaring people would venture hundreds of miles into an unknown land full of savages, or "skraelings." Furthermore, and more importantly, there is no scientific evidence to support this assumption. As Feder notes, foreign visitors bring with them a recognizable, foreign material culture. "Their unique and alien material culture represents, in fact, a signature of their presence, and similar evidence should be found in any other case where such a presence is to be verified" (Feder 91). With the exception of alleged runes scattered throughout the Midwest, there is no evidence that the Vikings discovered Minnesota. The most documented and well known source of evidence for the presence of Vikings before Columbus is the Kensington stone. However, I believe that the stone is a hoax for a number of reasons. First and foremost, having studied Swedish, I agree with what other scholars have already verified in that the inscription is of modern form. It is highly improbable that the Vikings spoke a language which in terms of its grammatical structure and lexicography, is comparable to modern day Swedish. For example, the word opdaglese appears on the stone. The word means journey of discovery in modern Swedish and according to linguists, did not appear for several centuries after the supposed date of inscription (Kensington home page). There are other fallacies within the inscription which attest to the runes invalidity including the use of English, as in the word 'ded', and the use of Arabic numerals which are considered to be historically out of context with the Viking era.
Besides the fact that the inscription is obviously a hoax, the circumstances surrounding the origins of the stone are also cause for suspicion. Believers in the stone claim that it could not have possibly been created by immigrant Scandinavians because they neither had the knowledge, nor the time to design such an elaborate hoax. However, as Blegen stated in his book, settlers did have knowledge of runes and some were in fact known to be pranksters (Blegen 113-4). Furthermore, farmer Ohman, who discovered the stone, did own a copy of a book depicting runes and their meanings. The enigma surrounding the origins of this stone, however, is not something that can ever be scientifically proved. Both sides propose differing viewpoints, and so it is important to look at the origins of the stone with considerable skepticism. One need not look to the origins surrounding the circumstances of the stone's first appearance, proof lies in the stone itself, a hoax identified by scholars who specialize in the field Viking history and linguistics.
Often people who make incredible claims are not able to back up their beliefs with real scientific research. Also, these people tend to have their books published by companies which do not adhere to such standards. A classic example is the book by Holand which was actually self published in his home town. Watch out for similar examples. Using the above examples I hope you are better able to see through the numerous hoaxes and "mysteries" which have unfortunately inundated our society. Good luck!!