Near Williston in Williams County, North Dakota — The American Midwest (Upper Plains)
Stepping "Off the Map" in the Louisiana Territory
The Lewis and Clark Expedition was the first major scientific venture funded by the United States of America. Mapping rivers was the principle stated goal of the Expediton. Water transportation was key to exploring the new territory's resources. At the beginning of the 19th Century, natural lakes and rivers provided only practical routes for moving major trade goods across a developing nation with almost no roads.
What geography did the explorers already know?
The Expedition carried a recent map
At Fort Mandan, Lewis and Clark used the long winter to gather much new geographic information from Native Americans of several tribes. From them, the explorers gathered details of the Missouri and its tributaries all the way to the Great Falls. They learned Native American names for the major tributaries and the order in which they would be encountered. Their knowledge of the Missouri River and its tributaries was very much improved, but still very incomplete.
The biggest question was the nature of the Continental Divide separating the Missouri River drainage from the rivers that went to the Pacific. There were incorrect predictions that the Divide was a single broken chain of mountains with easy passes or just a flat pyramid-shaped high plain. Maybe most of the major rivers were just a short portage from each other...or maybe not.
The Expedition's contribution
Compare the 1803 Arrowsmith map and the 1814 Clark map to see how much the "Voyage of Discovery" added to geographical knowledge of the American West.
Would President Jefferson have made the Louisiana Purchase if he had known that a razor-backed bulge of many high mountain ranges, hundreds of miles wide in places, split the continent? As they passed the future site of Fort Union, that realization was still four months away for Lewis and Clark.
The Indians inform that the yellowstone river is navigable for perogues and canoes nearly to its source in the Rocky Mountains, and that in it's course near these mountains it passes within less than half a day's march to a navigable part of the Missouri. it's extreem sources are adjacent to those of the Missouri, river platte, and I think probably with some of the South branch of the Columbia river. -- Meriwether Lewis, April 26, 1805
Erected by National Park Service, Lewis and Clark National Historic Trail.
Marker series. This marker is included in the Lewis & Clark Expedition marker series.
Location. 47° 59.972′ N, 104° 2.66′ W. Marker is near Williston, North Dakota, in Williams County. Marker is on Mondak Backroad 1 near 143rd Avenue Northwest (State Route 1804), on the right when traveling east. This marker is next to the entrance road for Fort Union Trading Post National Historic Site. Technically it is in Montana, but just by a few yards. It has been placed in North Dakota because of its proximity to and association with the Missouri-Yellowstone Confluence, Fort Union and other Lewis and Clark markers. Touch for map. Marker is at or near this postal address: 15550 North Dakota 1804, Williston ND 58801, United States of America. Touch for directions.
Other nearby markers. At least 8 other markers are within walking distance of this marker. River Interstates (within shouting distance of this marker); Gravel Pits (about 400 feet away, measured in a direct line); Lewis and Clark Trail (about 400 feet away); Dwelling Range (approx. 0.2 miles away); Bourgeois House (approx. 0.2 miles away); Riverboat Landing (approx. 0.2 miles away); Front Gate (approx. 0.2 miles away); Outpost on the Missouri (approx. 0.2 miles away). Touch for a list and map of all markers in Williston.
Categories. • Exploration • Waterways & Vessels •
More. Search the internet for Stepping "Off the Map" in the Louisiana Territory.
Credits. This page was last revised on December 6, 2019. This page originally submitted on December 5, 2019, by Barry Swackhamer of Brentwood, California. This page has been viewed 50 times since then and 2 times this year. Photos: 1, 2. submitted on December 5, 2019, by Barry Swackhamer of Brentwood, California.