Vikings or their predecessors traveled far more extensively and earlier than many people think. There are hieroglyphics in Runestone State Park in Heavener, Oklahoma http://www.oklahomaparks.com/detail.asp?id=1%2B5U%2B5325 long before the Spanish or French explored the area.
Might not want to bet on that, though. According to Dr. William Savage, the professor who taught Oklahoma history at OU a few years ago, there are no viking artifacts associated with the Heavener Runestone. Just the carvings themselves. My personal opinion of Savage is that he’s a jerk, but a competent and knowledgeable jerk. He’s certainly an entertaining lecturer...