Pikes-party-encountered-Indians-headwaters-Mississippi-River-AMHP-Winter-23 Meeting Across the River. In 1805, Pike, at the time leading a water-borne exploratory party, encountered Indians at the headwaters of the Mississippi River. (Ullstein Bild/Ullstein Bild Via Getty Images) Ullstein Bild/Ullstein Bild Via Getty Images