David Thompson's Journey: U.S. States and Canadian Provinces Traversed

Fur Trade Explorer's Route (1797–1812)

David Thompson, "greatest land geographer," mapped ~3.9M km² for North West Company. His travels crossed:

United States (Present-Day)

• North Dakota — Mandan villages, Missouri River.
• Montana — Rocky Mountain foothills, Kootenai River.
• Idaho — Pend Oreille, Clark Fork, Columbia River headwaters.

Canada (Present-Day)

• Alberta — Rocky Mountain House, North Saskatchewan River, Athabasca Pass.
• British Columbia — Columbia River to Pacific (first European to navigate full length, 1811).

Additional Territories (Historical)

• Assiniboia (Red River Colony, now Manitoba).
• Saskatchewan (North West Company posts).
• Washington/Oregon (Columbia River—then Oregon Country, disputed).

Legacy

Thompson's maps (1814, 1826) remained authoritative for decades. His Columbia River survey enabled later settlement and the 1846 Oregon Treaty boundary.