The Journal of San Diego History

The Journal of San Diego History

“La Mojonera” and the Marking of California’s

U.S.-Mexico Boundary Line, 1849-1851

Charles W. Hughes

Winner of the Marc Tarasuck Award

On a bluff overlooking the “Arroyo de Tia Juana” several hundred feet up from

the shoreline of the Pacific Ocean, a boundary monument—La Mojonera—has

marked the start of the 1,952 mile line separating Mexico and the United States

for the last 156 years. Captain Edmund L. F. Hardcastle, of the U.S. Topographical

Engineers, and Ricardo Ramírez, a zoologist and botanist attached to the Mexican

Boundary Commission, dedicated it on July 14, 1851.^1 Today it is one of 276

monuments marking the boundary line running between El Paso, Texas, and the

Pacific coast.

Charles W. Hughes is a local historian currently studying the history of California’s U.S. Mexico border.

He gratefully acknowledges the research assistance provided by the staffs of the Oceanside and San

Diego public libraries, San Diego State University Library, and the National Archives.

John Russell Bartlett’s 1852 drawing of the Monument at the Initial Point on the Pacific from Bartlett’s Personal

Narrative of Exploration and Incidents in Texas, New Mexico, California, Sonora and Chihuahua (1854).

©SDHS, OP#17134.