The river was explored during the Lewis and Clark Expedition and named after their guide, Sacagawea. The river was named after her because she was in a canoe, and got caught in a storm. The canoe nearly tipped over, the expedition members were trying to balance the boat, but Sacajawea collected all the books, records, and instruments from the journey. They may have been covered in some material which prevented water damage. The river was named after her for this deed.
