On May 17, 1673, Father Jacques Marquette and fur trader Louis Joliet set out on a four-month voyage that carried them thousands of miles through the heart of North America to explore the path of the Mississippi River. Their voyage helped to initiate the first non Native-American settlement settlements in the North American interior that introduced Christianity into 600,000 square miles of wilderness, gave French names to cities from La Crosse to New Orleans, transformed traditional Indian cultures, and nearly exterminated the fur-bearing mammals of the Upper Midwest.