After the United States’ victory in the Mexican-American War (1846-1848), both countries signed the Treaty of Guadalupe Hidalgo giving the U.S. more than half of Mexico’s original sovereign territory.

U.S. expansion into the West began with President Jefferson's 1803 Louisiana Purchase and culminated during President Polk's administration with the annexation of Texas and victory in the Mexican-American War. It was a controversial and unpopular war and considered a land grab by many, but it brought California and much of the Desert Southwest into the American fold.

When the question of California’s geographical size and official borders came up at the state’s first Constitutional Convention held in Monterey in October 1849, there were two main options considered. One called for including all of what Mexicans called Upper California, which included a big chunk of the Great Basin as well as portions of present day Utah and Arizona.

Many of the delegates, however, preferred a more manageable border in the Sierra Nevada, for both political and practical reasons. The possibility of an uber-state later being politically carved into slave territories was one serious concern.

Among those pushing for a state line along the Sierra Range was none other than John C. Frémont, credited as the first Euro-American (along with his cartographer Charles Preuss) to see Lake Tahoe. Frémont was also a strong proponent of California entering the Union as a free state, not slave. Considering that Frémont had already seen the size and beauty of Tahoe (he called it Lake Bonpland), the topographical engineer probably assumed that the important lake would be totally included on California’s side of the boundary.

John C. Frémont's 1848 map illustrates the general contours of the Sierra Nevada. Courtesy Barry Lawrence Ruderman Antique Maps, Inc. 

Finally, one of the delegates called for an eastern border fixed in the mountains, but based on longitude and latitude, not geography. The delegate himself had no concept of Sierra Nevada topography and hydrology when he made his suggestion and despite the lack of a survey the convention submitted to Congress an eastern state border based on an imaginary grid, not the ground. This ill-conceived action by a few has caused headaches and confusion for Nevada and the federal government for decades. Bi-state water rights issues on the Truckee River continue to this day.

Two of California’s boundaries were no brainers; 42nd degree latitude for the northern border (based on an earlier agreement incorporated into the Oregon Territory treaty when Great Britain relinquished all claims to the present-day Pacific Northwest), and the Pacific Coast (including all the major bays, harbors and offshore islands). California’s southern state line would be run right down the middle of the Colorado River and then along the 35th parallel on the border with Mexico, but it was the eastern boundary that gave everyone fits.

Shaded area indicates trouble zone for California and Nevada's shared border. Nevada Territory was established in 1861 (after the 1859 discovery of the Comstock Lode) when the federal government split Utah Territory in half. Note how additional Mormon land was ceded to Nevada, which gained statehood in 1864. Map courtesy John P. Wilusz from his article published in Professional Surveyor, January 2002.

On October 11, 1849, the youngest delegate attending the convention, James M. Jones, offered a land description of the eastern border which was adopted and incorporated into the state constitution. The description started at the northeast point of the state at the intersection of the 42nd degree latitude at the 120th degree longitude, and then “…running south along the 120th degree longitude until it intersects the 39th degree of north latitude [an intersection that falls within Lake Tahoe]; thence running in a straight line in a southeasterly direction to the Colorado River… “

Jones description placed Lake Tahoe and its water, which flows into the Great Basin, not the Pacific Ocean, directly in the crosshairs of dispute and disagreement between California and the future state of Nevada. The 1848 Treaty of Guadalupe Hidalgo not only described the new international boundary between the United States and Mexico, it required each government to commission a survey to run and mark the boundary line on the ground. The California convention delegates skipped this important step. When the first survey to mark the state’s eastern boundary was completed in 1863, they were surprised to find that only two-thirds of Lake Tahoe actually fell within the new state border, with one third in Nevada.

Running the state line through Lake Tahoe (see Nugget #238 for the history behind the name) generated controversy and conflict between California and Nevada over water rights.

More surveys were undertaken in the 1860s and 1870s and each found discrepancies with previous work. In 1872, the federal government hired astronomer and surveyor Alexis Von Schmidt to improve the results. Part of the challenge for these early surveyors (besides rugged topography, hostile Indians, lack of funding, and an aggressive schedule) was the difficulty of locating geographic coordinates, especially longitude.

Of the two coordinates, latitude is the easiest to determine using astronomical observations and scientific instruments, but longitude is a function of time based on global meridians in relation to Greenwich, England. At the 39th degree latitude (Lake Tahoe) a clock error of only one second would cause a surveyor to post his longitude marker nearly a quarter of a mile out of position. Von Schmidt faced challenges similar to his predecessors, but he had an important advantage when it came to determining longitude. By 1872, accurate time signals could be transmitted by telegraph from San Francisco. The wires followed the transcontinental railroad tracks and crossed the border near Verdi, Nevada.

Diagram defining the border calculations. Courtesy John P. Wilusz, PE, published in Professional Surveyor, 2002.

In addition to the technological challenges, Nevada caused more problems when it passed the Organic Act. Instead of simply recognizing California’s existing eastern border as its western margin, this act demanded California give up any land associated with waters that “did not flow into the Pacific.”

The congressional acts that created Nevada Territory (1861) and the State of Nevada (1864) provided for a western boundary at the Sierra Nevada crest line if the California state legislature would agree to change its existing boundary from 120 degrees longitude. California, however, declined to relinquish any territory, particularly its portion of Lake Tahoe which is located east of the Sierra crest line.

North Lake Tahoe survey monument from Alexis Von Schmidt's 1872 survey.

Lake Tahoe was not the only casualty from this early confusion. The so-called Roop County War took place when residents near the disputed state line around Honey Lake near Susanville in northeastern California proclaimed themselves in a separate territory. Their independence freed them from California law and taxes. It took a heavily-armed, 90-man militia from Plumas County to enforce California’s jurisdiction, but after two days of fighting the defeated rebels became part of Lassen County.

A hydrological border along the Sierra crest would have mitigated many of the controversial issues of watershed management along the eastern Sierra front, with Nevada having control over vital water sources emanating from the “California Mountains.” Fortunately, over the past 150 years bi-state agreements and federal decrees have solved many of the problems associated with a state boundary that does not take into account physical features like streams, lakes, and rivers.

Special thanks to Guy Rocha, retired Nevada State Archivist, for his prior research into this topic.




























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