Tri-Territory Historic Site

One of the plaque's three neighbors is misnamed. The land west of the divide and north of the parallel was the Oregon Country, which became wholly American when the Oregon Treaty with Britain split it at the forty-ninth parallel in 1846; the Northwest Territory was the Old Northwest of 1787, around the Great Lakes. South of the line was Mexico's until the Treaty of Guadalupe Hidalgo ceded it in 1848. The forty-second parallel itself was drawn in 1819, when the Adams-Onís Treaty fixed it as the border between Spanish and American claims.

What the plaque says

Tri-Territory Historic Site Marking the common boundary of the Louisiana Purchase (1803) the Northwest Territory (1846) and Mexico (1848). The site is located where the Continental Divide crosses the 42 parallel north latitude. Dedicated September 24, 1967 by the Kiwanis Clubs of Lander, Rawlins, Riverton & Rock Springs, Wyoming

Where it stands

Worth the stop nearby

• Boar's Tusk and the Killpecker Dunes — 15 mi
  The throat of a vanished volcano made of rock from the mantle, standing over a fifty-five-mile river of dunes that crosses the Continental Divide.

More markers nearby

• Parting of the Ways — 21 mi
• Almond Overland Stage Station — 23 mi
• Rough Travels — 23 mi
• Overland Stage Route (Point of Rocks) — 23 mi