Yellowstone Mouth by Air

Strong northwest winds had slowed the expedition’s progress for several days. Late in the morning of 25 April 1805, Lewis decided to proceed overland to the mouth of the Yellowstone River, which he had deduced from the Indians’ geographical description would be “at no very great distance” ahead. Within a few hours, with time out for a lunch of fresh, tender buffalo calf meat, the Missouri’s greatest tributary came in sight. “I ascended the hills,” Lewis wrote, “from whence I had a most pleasing view of the country, particularly of the wide and fertile vallies formed by the Missouri and Yellowstone Rivers.”

That night Lewis and his small party camped a short distance up the Yellowstone. We could surmise from Lewis’s description that the site was near the third island from the bottom in this photo, but the meeting place of the two rivers has changed so much over the past two centuries that it is impossible to pinpoint the location with certainty. The orderly rows of cottonwood trees on the near shore and on the point between the rivers record the successive high-water marks of recent decades.

The Crow people still call the river Me’,-ah’-zah, Elk River, but sometime late in the eighteenth century it acquired the French name, Roche Jaune, or Yellowstone. Here, flowing northward, it runs almost parallel with the North Dakota-Montana border, completing its unimpeded six-hundred mile flow from the mountains in Yellowstone National Park.

The next day, 26 April 1805, the Corps reunited on the point of land between the two rivers, “all in good health, and much pleased at having arrived at this long wished for spot.” The captains issued “a dram”—four ounces of whiskey—to each person, which generated song, dance, and general hilarity, and the men “seemed as perfectly to forget their past toils, as they appeared regardless of those to come.”

This photo was shot in May 2000, when both rivers were laden with silt from spring runoff, the Yellowstone (left) especially.