The boundary it anchors was established by the Treaty of Guadalupe Hidalgo, which ended the Mexican-American War in 1848. Under that treaty, Mexico ceded to the United States roughly half of its territory — the lands that would become California, Nevada, Utah, Arizona, New Mexico, Colorado, and parts of Wyoming. The border was to run from the Pacific coast eastward along the southern edge of California and the Gila River. A joint boundary commission was tasked with surveying and marking the line on the ground, a project that began in the late 1840s and required years of work across challenging terrain. The first monument at the Pacific end was erected in the early 1850s, though the exact location and form of that original marker has been the subject of subsequent adjustment.

The current monument — a white-painted concrete obelisk — is not the original structure. The first marker at the Initial Point was a simple boundary post. The present monument was constructed in 1894 by the International Boundary Commission as part of a systematic resurvey and re-monumenting of the entire border. It stands approximately 60 meters from the Pacific Ocean on a bluff that drops to the beach below. The monument sits within Friendship Park, a binational public space where families separated by immigration enforcement have historically met across the fence line, reaching through gaps in the barrier to touch hands with relatives on the other side. The park's character has changed as successive layers of border infrastructure have been added around and through it.

For most of the twentieth century, the border at this point was relatively open — a line on a map rather than an impermeable barrier. During the 1990s and 2000s, physical border infrastructure expanded substantially in the San Diego–Tijuana sector. The Secure Fence Act of 2006 mandated additional barriers, and construction proceeded in phases. Today Monument No. 258 is surrounded by two parallel border fences, the space between them patrolled by U.S. Border Patrol. The monument itself remains accessible from the Mexican side; access from the American side at Friendship Park has been restricted and at times eliminated entirely depending on the policy of the moment. The monument stands where it has always stood, watching the fences accumulate around it.

From the air, the border at this point is visually dramatic: the double fence line running from the bluff into the surf, the monument visible as a white speck against the beige hills, the Pacific stretching west to the horizon. The beach on the American side is accessible only through Border Field State Park, at the southern end of the Tijuana River estuary — a protected wetland that provides critical habitat for several endangered bird species. On the Mexican side, Playas de Tijuana is a residential neighborhood with a popular beach promenade. The Initial Point of Boundary was chosen where it was chosen because the surveyors started at the ocean and worked east. The ocean they chose, the Pacific, does not care about the line.