The Online Encyclopedia of Wyoming History

The Hinge of the West

The Hinge of the West

By Dick Blust, Jr.

Geography, of course, is fundamental to all aspects of history, and in few cases is this more profoundly true than in the American West. Arguably, the most significant—in an emblematic sense, at least—is the Tri-Territory Historic Site in Sweetwater County, Wyo., where the Louisiana Purchase, the Oregon Country and the Mexican Cession all joined at a single spot along the Continental Divide. Those three acquisitions, with the last coming in 1848, became the overwhelming bulk of the western United States outside of Texas.

Map of the modern United States, with its sequence of acquisitions overlaid. The Tri-Territory Historic Site lies at the intersection of the 42nd parallel of north latitude and the Continental Divide in what’s now southwest Wyoming. USGS map.

Last fall, along with Dave Mead, executive director of the Sweetwater County Historical Museum in Green River, I traveled to the site to photograph it. It’s a lonely place and the vista is breathtaking in any direction, which helps us get a handle on the West’s elemental  fact:  its immensity. Dave and I talked about the fact that we were standing—figuratively and, in a way, even literally—at its center. 

Look at a map of the United States and imagine a circle with a radius of roughly 900 miles with the Tri-Territory monument at its center. Within that circle are the states of Oklahoma, Kansas, Nebraska, South Dakota, North Dakota, Colorado, Wyoming, Montana, Idaho, Washington, Oregon, California, Utah, Nevada, New Mexico and a portion of Texas. As such, the site serves as the base of a great hinge, whose long, sweeping arm extends east to St. Louis, south to the Rio Grande, west to the Golden Gate, and north to the Canadian border:  the Hinge of the West.

The Tri-Territory Site may be symbolic, but it is nonetheless a vital symbol. There the holdings of three empires combined to form what is, for many of us, the most important part of the United States. The morality and the means of how we came into possession of these immense tracts will always be the subject of intense debate, but it is impossible to imagine an America without the West.