The spring rains had swollen the Platte River and made it very difficult. Driving the livestock across was a simple matter, the real problem was the wagons and heavy baggage. They found an Indian canoe that was large enough to carry about six hundred pounds. Narcissa wrote: “We stretched a rope across the river and pulled the goods over in the canoe without much difficulty” [Letter 26]. In this same letter to Whitman’s brother, Augustus, Narcissa said: “Husband became so completely exhausted with swimming the river on Thursday, the 19th, that it was with difficulty that he made the shore the last time. Mr. Spalding was sick, our two hired men good for nothing.” The Fur Company’s caravan was four days ahead of them and unless they caught up with them before coming to the Pawnee Indian village, it would not safe to travel without the escort.
Some additional facts about the Pawnee Indians. http://www.warpaths2peacepipes.com/indian-…/pawnee-tribe.htm