Tri-Territory Site

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Atop Steamboat Mountain in Sweetwater County, Wyoming where the 42nd Parallel crosses the Continental Divide you will find a pyramidal stone monument. The monument documents the “Tri-Territory Site” with a bronze plaque testifying to the geographic location of the coincidence of three very important occurrences in the history of the expansion of “The West” United States of America.

The first half of the Nineteenth Century was a time of great excitement about what was west of the Mississippi River, that great, mostly unexplored land that was yet to become part of the United States. This vast wilderness was, in fact, claimed in part by Spain, France, England, Mexico and Texas Republic and was inhabited by many Native American tribes and numerous, thus far unfamiliar, wild animals.

No one was more curious or excited about what great adventure and discoveries laid in that mysterious “West” than President Thomas Jefferson. He rued the fact that his political duties forbade his own expeditions into that uncharted land. He, having been a surveyor in his youth, would have loved nothing more than to survey and map the new territory and record its geology, flora and fauna. But, alas, this was not to be so. The next best way to satisfy his yearning for this great adventure was to groom a prodigy to carry out his quest for knowledge and imperialist ambitions. That chosen person was Captain Meriwether Lewis. Jefferson personally tutored Lewis in mathematics and in the use of surveying instruments of the day and sent him to scientists in Philadelphia for studies of botany, celestial navigation, zoology and medicine; all in preparing him to lead an expedition into the “West”. Captain Lewis chose William Clark to be co-commander of the Corps assigned to make this expedition and insisted that Clark be assigned the rank of Captain to make sure they were equally in charge.

President Jefferson issued orders to the two Captains to “explore the whole line [of the Missouri] even to the Western ocean” and on May 14, 1804, the Corps of Discovery, in a keelboat and two pirogues, embarked on an unbelievable expedition up the Missouri River. Thus, barely six months after congress ratified the sale of the Louisiana Territory (October 1803) from France to the United States, did the co-commanders of the Corps of Discovery unveil President Jefferson’s dream of making America a world power by expanding the Empire from “sea to shining sea”.

The Discovery mission took the Corps beyond the extents of the Louisiana Territory to the northwest where laid a vaguely defined region known as Oregon Country. This was a wild, uninhabited (by white men), Indian controlled region traversed by the Columbia River, claimed in shadowy documentation by France, Spain, Great Britain, Russia and the United States. George Vancouver explored Puget Sound in 1792 and claimed it in the name of Great Britain. In 1807-08 David Thompson and Simon Frazier explored much of the lands and rivers contributing to the Columbia River and in the summer of 1811 Thompson became the first known white man to traverse the length of the Columbia. On July 11, 1811, Thompson’s group camped at the confluence of the Snake River and the Columbia and it was there that Thompson claimed the country for Great Britain by erecting a pole monument with such notice and a declaration that a trading post would be erected at the site. Thompson continued his survey of the Columbia in that same year culminating at the still under construction Fort Astoria at the Columbia River Bar on the Pacific Ocean. Besides the Lewis and Clark expedition the United States based its claim to the region partly on Robert Gray’s exploration into the mouth of the Columbia in 1792. Spain’s claim was based on old treaties such as the Treaty of Tordesillas and Inter caetera of 1493-94 plus their explorations of the coast during the late 1700s. Spain later, through treaty, granted Great Britain rights to the northwest without relinquishing its claim to the territory or establishing a northern border for Spanish California. Then, as part of the Adams-Onis Treaty of 1819, Spain relinquished any rights remaining to the United States for territory above the 42nd parallel. Russia followed in the 1820s, in separate treaties with Great Britain and the United States, giving up its claims to any territory east of the 141st Meridian and south of 54°40′ parallel. Thus, that left only the United States and Great Britain contesting the rights to the territory and as a result of the Anglo-American Convention of 1818 the two countries agreed to "joint occupancy" of that territory between the Pacific Ocean and the Rocky Mountains. Settlement of the Oregon Country grew dramatically with trappers exploiting the rich populations of beavers and other fur bearing animals. This growth was soon expanded on by settlers from the east via the Oregon Trail in the late 1830s. Competition between Great Britain and the United States grew as a result of settlement of Americans from the east and British Canadians from the Red River country settling on farms near Fort Vancouver. This grew into what was known as the Oregon Boundary Dispute. Despite much haggling over where to divide the territory into United States and British Columbia and with no desire by either country to go to war again, an agreement was reached with the Oregon Treaty of 1846. This treaty divided the territory west of the Continental Divide along the 49th parallel to George Strait, leaving all of Vancouver Island under British control. That border remains today.

Meanwhile, as this destiny of Oregon Country was proceeding, many American settlers and Tejanos (Mexicans living in Texas) in Texas, which was a part of Mexico at the time, were unhappy with rule by Santa Ana, Mexico’s President, and decided to fight for Texas independence. After Santa Ana beat down the Texans at the Alamo, Sam Houston led a Texan army that captured Santa Ana in a battle at San Jacinto. As the result of Santa Ana’s release, Santa Ana gave Texas its independence. President Van Buren, for various reasons, was against annexation of Texas but in 1845 when James Polk became president that all changed and Congress voted to annex Texas. Annexation caused a dispute over the border between Texas and Mexico and Congress declared war with Mexico in 1846. The war continued until September 1847 when America captured Mexico City. Then in February 1848 the two countries came to an agreement and signed the Treaty of Guadalupe-Hidalgo in which Mexico recognized Texas as a state of United States and ceded a large part of Mexico to the United States for about fifteen million dollars. This deal known as the Mexican Cession deeded lands to the United States that would later become Utah, Nevada, California, and parts of Arizona, New Mexico, Colorado and Wyoming.

Thus, through war, treaty, extraordinary bravery and tenacious pioneering these three pieces of the United States mosaic were added and President Jefferson’s dream of a United States "from sea to shining sea" was realized.

Believing that these three significant events in U.S. history and their coincidence lying in southwestern Wyoming merited some form of recognition, the Kiwanis Clubs of Rock Springs, Lander, Riverton and Rawlins, acting in cooperation with BLM officials, conceived a plan to erect a monument at the site where the three acquisitions meet.

A 24"x18" bronze plaque is mounted on a native stone masonry monument at the determined location. The site is enclosed in a fenced area also containing four flag poles, for the four nations involved, and a BLM interpretive sign. Elevation of the site is 7,775 feet.

The position of the coincidence of the three historical acquisitions was established by B.L.M. cadastral survey in July 1967, determined from G.L.O. Station No. 25 (Sweetwater County, C.I. Asinkson, 1931) by traverse through section lines adjusted to sea level distances. The position is 42 feet east along the 42nd. Parallel from the section line between Sec. 1 and Sec. 2, T23N, R102W. The 42nd Parallel lies 1315.6 feet southerly (S0°05’E) from the NW Section Corner of Section 1, T23N, R102W.

There was an attempt by the Kiwanis Clubs and the BLM to include the Tri-Territory Site in the National Register of Historic Places. BLM officers vigorously pursued the proposal through the Wyoming Recreation Commission. The Commission cited two weaknesses in the BLM proposal one of which could be corrected and another "which can be in no way avoided". The first weakness to the proposal, that which could be corrected, was the wording on the plaque which read, in part "…Louisiana Purchase (1803) The Northwest Territory (1846) and Mexico (1848)". The reviewing historian, Ned Frost, correctly pointed out that "The Northwest Territory" is an incorrect reference to that region of the Tri-Territory acquisitions. In all histories of the United States, "The Northwest Territory" was the area that was to become the States of Ohio, Indiana, Illinois, Michigan, Wisconsin and a part of Minnesota. The correct designation should be, "Oregon Country". The second weakness to the proposal was that the site "is not in itself a place at which any historic event occurred". Because of these "weaknesses" and other bureaucratic obstacles the nomination was vetoed. No attempt to change the wording on the plaque or to militate the other deficiencies in the nomination has to date been attempted.

Because of the importance of these acquisitions to the United States and the proximity of their common enjoinder it seems only logical that the site be recognized in some national historic archive as a place of distinction.

The BLM has recognized the historic relevance of the site and the importance to provide the public access to it by posting direction and distance signs from both highways 191 and 28 to the site.

Harry J. Kessner, PE, PS, earned his civil engineering degree at the University of Wyoming. After graduation he spent two years active duty and six year reserved duty in the U.S. Army. He was project engineer/ division engineer for the Union Pacific RR; branch manager for Bennett-Carder Assoc. providing engineering and surveying services; and owner and president of Loham Walsh LLC. Today he enjoys semi-retirement in the Eastern slopes of the Wind River Mountains at Lander, Wyoming.

A 1.412Mb PDF of this article as it appeared in the magazine—complete with images—is available by clicking HERE