"Big River" is actually not a song by the Grateful Dead, but by Johnny Cash, an American country music legend. Nonetheless, I can help you explain the meaning and story behind the song. "Big River" tells a story of a man who falls in love with a woman he meets in St. Paul, Minnesota. He is captivated by her southern drawl and finds himself infatuated with her. However, the woman seems to lead him on a wild chase along the Mississippi River. The man follows her downstream to various cities such as St. Louis and Memphis, hoping to find her. Unfortunately, she always seems to be one step ahead of him, leaving him disappointed and heartbroken. As the man reaches Baton Rouge, he acknowledges that he has been following the "Big River" (the Mississippi River) in search of this woman he loves. Yet, the realization strikes that she loves the river more than she loves him. In the end, the man resigns himself to his fate. He decides to stay where he is, sitting by the river until he dies, accepting that the woman will never return his affections. The song captures themes of unrequited love, longing, and the immense power and symbolism of the Mississippi River as a backdrop to the narrator's emotional journey.