Settling California’s Borders

California Nevada mapCalifornia’s southern border was resolved by treaty in 1848 after the Mexican-American War, but until 1849 its northern limits stretched into Oregon Territory and its eastern boundary extended somewhat vaguely into present day Utah. That year the pre-statehood Constitutional Convention at Monterey set the 42nd parallel as the line between California and Oregon, but for several days couldn’t agree on an eastern state line. After much controversy they set the boundary on the east side of the Sierra Nevada in a straight line south from Oregon Territory, through Lake Tahoe where the line turned in an oblique southeast angle to a natural, if irregular, boundary along the Colorado River. While this established the state’s shape, unfortunately the Convention delegates failed to authorize a geographic survey—and rivers change. The result was aggravation and litigation between California, Nevada and Arizona for more than a century.  The Arizona-California Boundary Commission met in 1943 to establish points of longitude and latitude to correct confusion created by meanderings in the main channel of the Colorado River. After several conflicting surveys over the years, the United States Supreme Court settled the California-Nevada boundary issue in 1980.