One cannot remain in Claremont for long without sensing the dominance of Mount Baldy over the landscape. From the broad, gently sloping valley below, its rocky peak is visible for miles, only ever obstructed by the clouds that seem to linger around it. From these clouds, the mountain’s distinctly smooth, curved face collects the headwaters of San Antonio Creek, which over eons eroded a path through the foothills, clearing the canyon that provides Claremont with its impressive views of the creek’s source.
A line descends from the peak of Mount Baldy. From the mountaintop, it traces a path no land animal could ever follow, its almost entirely straight course jutting up and down hillsides and cliffs and cleanly bisecting the alpine village of Mount Baldy, California. Leaving the wilderness, the line continues unbroken through the urban Pomona Valley, barreling down roads and cleaving through houses as it approaches its forgotten endpoint, a black willow tree felled at least 160 years ago.
The line dividing the county of Los Angeles from the county of San Bernardino does not bend to the forces of nature; it does not bend to the will of Claremont McKenna College, whose Roberts Campus Sports Bowl straddles the cities of Claremont and Upland. Men have dreamed of rerouting the San Antonio Creek, which meanders nearby; a few have succeeded. But since the Los Angeles County line was arbitrarily fixed by 19th-century surveyors, it has been immovable. The City of Claremont and its neighbors do not truly owe their existence to the creek, nor even to the mountains; they owe it to the line.
Of course, people lived in what is now Claremont for millennia without creating administrative boundaries. But today, their lives depend on them. With the sole exception of the mountain itself, practically everything associated with the modern name “Claremont” was created consciously by property owners and governments seeking to reshape the Pomona Valley in their own image. The city’s tree-lined streets, its lush parks and its nostalgic architecture are all aberrations in Southern California, cultivated at great expense by the city and by the Colleges. This dream of Claremont ends at the city limits. Crossing into a neighboring city, one enters the competing vision of a different set of institutions, shaped through different policies.
From its very beginning, this project was a project of line-drawing. Eventually, once Claremont and its neighbors had formed and evolved into suburban centers, these lines would be drawn to shape existing communities; that story may be the subject of a future article. But the oldest of these lines were drawn long before anyone could have imagined a city, by settlers just beginning to familiarize themselves with the abundant open land around them. Some of these boundaries were superseded over time; others would reshape the land around them for centuries to come. Those that came to comprise the Los Angeles County boundary, a boundary which cities are not legally allowed to expand across, date to the very origin of private property in the region.
Tongva people had prospered in the sunny, gently sloping landscape of the Pomona Valley for centuries, but there were no property lines in the open grazing lands between their towns. Even their enslavers under the 18th-century Spanish mission system did not divide the land amongst themselves; by and large, the valley was simply not a settled place. Even the waters of the San Antonio Creek were not settled, periodically altering their course just as the travelers and animals did along the roads that passed through the area on the way towards the coast.
After Mexico gained its independence, it quickly came under increasing pressure to establish a more permanent presence in the northern, inland territories, which would be conquered by the United States years later. The mission system had already established bases in the region, but for the new nation to reshape and exploit the land, it would need to incentivize larger-scale, secular settlement. In the 1830s, the Mexican government began creating ranchos in what is now Southern California, granting enormous tracts of this frontier land to private owners who would have to make them useful for agriculture with little government support. By giving away this land in exchange for investment, they effectively induced colonization by drawing the first lines to divide the region.
The surveying of the first boundaries in the wide-open Pomona Valley was done with primitive technology but considerable ceremony. When Ygnacio Palomares and Ricardo Véjar received permission from the Mexican government and the nearby San Gabriel Mission to settle the area, they were granted two square leagues, or about 16 square miles, of land, which would become known as Rancho San José. They set out for the remote area with their families, accompanied by a mission priest, and upon arrival, they searched for recognizable landmarks that could become the corners of the property. To determine whether the area between the corners was equivalent to the two square leagues they had been granted, two men from the party performed a survey on horseback, traveling between the corners with a stake connected to a coiled rope of a known length. Planting the stake at a starting point, one would ride out with the rope until it ended. Then, they would replant the stake there, adding up the approximate distance between the corners.
In this way, on March 19, 1837, the first portion of what would become the Los Angeles county line and the Claremont city limit was determined by a single horseback journey. It began at a black willow tree near the western bank of the San Antonio Creek, which Palomares and Véjar’s men marked by leaving a dry, cross-shaped stick between its limbs. From there, the men rode west into the hills, cutting into a tree near where Cal Poly Pomona now stands to mark it as another corner. Then, they returned to the banks of the San Antonio Creek, where they found a pair of cottonwood trees with crossed branches several miles upstream of the black willow. These three landmarks formed a triangle which, with later additions, became the legal boundary of Rancho San José.
The following decades were a tumultuous time for Southern California. Conquest by the United States and the subsequent California Gold Rush brought an unprecedented wave of settlers to the area, and the new government did not strictly abide by its promise to respect the existing property rights of former Mexican citizens or Tongva towns. Titleholders were required to reclaim their holdings with new, more accurate surveys of the increasingly valuable land they had been granted under the Mexican system, leading to expensive legal battles that weren’t fully resolved until the 1940s.
Across the state, families lost their land and savings — but at the same time, new arrivals grew prosperous and demanded changes to the political geography of the area. Once, all of Southern California had been included in either Los Angeles County or San Diego County; there were simply no other settlements in the region large enough to govern from. But as the area, still overwhelmingly rural and known as the “cow counties,” developed, groups of settlers wary of making the long journey to Los Angeles to conduct business increasingly clamored for their own county governments.
The Mormon settlers who founded San Bernardino, California, only arrived in Southern California in 1851. By 1853, they were secure enough to elect Jefferson Hunt, a church leader, as one of two State Assemblymen from Los Angeles County. Almost immediately, he petitioned to create a new county in the east, centered on San Bernardino and encompassing the various roads that led from the Los Angeles area through the desert towards Arizona and Nevada. The state legislature quickly agreed and set about defining a boundary between the two counties.
With little precise knowledge of the area’s geography, they chose to follow existing property lines where possible — including the boundary of Rancho San José and of the nearby Rancho Cucamonga, which ended on the other side of the San Antonio Creek further north. The boundary would then continue through the hills to Mount Baldy, the highest point in the region, where it would turn directly north into the vast inland desert.
Thirteen years later, United States Deputy Surveyor George H. Thompson mapped Rancho San José, formally surveying this portion of the county line for the first time. To the east, the property line still began at a “grey granite rock … in the Arroyo San Antonio at a point 9700 varas [Spanish yards] in a direct line from the place designated by as a large rock in the center of water pool agreed upon as the place where the Black Willow once existed.” The boundary bent slightly for a sycamore tree and at a “Redwood Post in earth mound” — and it still does to this day, as it does for similar landmarks at the western edge of Rancho Cucamonga further north. When surveyors finally mapped the county boundary itself in 1878, they simply drew straight lines between all of these landmarks and Mount Baldy, either ignoring or misinterpreting the legislature’s specification to follow natural geographical features between them. The line dividing the Pomona Valley has not changed since that day, when an 1878 survey misapplied an 1853 law based on lines measured on horseback in 1837.
Today, the county line is difficult to see but easy to feel. Almost immediately east of the Claremont Colleges, as one crosses Claremont Boulevard or Mills Avenue, the landscape dramatically shifts. Within half a mile, Sixth Street unrecognizably transforms from a two-lane, shady street to a wide road (renamed to Arrow Route) with unpaved sidewalks and container trucks parked along its shoulder, passing through open fields and warehouses as well as newly built commercial and residential developments. While similar changes happen at Claremont’s other boundaries as one grows further from the disproportionately wealthy, white and privileged neighborhoods surrounding the Claremont Colleges, nowhere else were these boundaries cemented long before the city even existed — and nowhere else do they present such a barrier for collaboration between Claremont and its neighbors.
Claremont is part of the Pomona Valley Transportation Authority (PVTA) and in the service area of Los Angeles Metro and Foothill Transit, which therefore provide 7C students with many public transportation options. But these services awkwardly cut off just past the county line in the neighboring city of Montclair, where Claremont and PVTA recently ended Dial-a-Ride service. From the other side of the line, Montclair’s unsympathetic San Bernardino County peers recently voted to cancel funding for a Los Angeles Metro stop, forcing the future A Line extension to end at Claremont as well. The very name of Montclair, an obvious reference to its more prominent neighbor, seems to bemoan its position of being stuck hopelessly between the two counties.
Shortly before Claremont wielded the county line to cut costs by excusing itself from subsidizing students’ Uber shopping trips across the line to the Target in Montclair, the city made a similar decision that is much harder to justify based on political tropes alone. On July 1, 2025, Get About, a longer-distance Dial-a-Ride service offered jointly by Claremont, Pomona, La Verne and San Dimas exclusively to seniors and people with disabilities, more than doubled its fares and cut its service into San Bernardino County, which had mostly provided transportation to and from medical facilities. Now, elderly and mobility-impaired residents would have to seek alternative transportation to continue receiving the healthcare they were accustomed to.
This is not a decision any city would take lightly; retirees famously wield great power in affluent municipal governments. But as then-Claremont Mayor Corey Calaycay, a member of the PVTA board and currently a City Council member, stated, the cost of the service had simply become too great for its constituent cities to bear. The identity of Dial-a-Ride users was an important factor in structuring the cuts, but it was not the most important factor. Faced with limited and uncertain resources, the City of Claremont made the choice almost any government would: It prioritized transportation within its own borders.
Despite the efforts of constituents and politicians, no factor matters more to how cities are governed or, at least in the United States, has less basis in any present economic, cultural or geographical reality than their city limits. American suburbia is the final frontier of a frontier nation; within it, municipal governance is the ultimate manifestation of a federalist political tradition that upholds self-determination and the protection of entrenched rights above all else. Claremont is far from unique among the scores of cities which, porous in reality, have had their boundaries on paper hemmed in by lines drawn for no purpose but to divide what was once abundant. But if nothing else, the long afterlife of a tree felled generations ago shows just how profoundly the Pomona Valley has changed in a few short centuries — and just how capriciously those cast into history have selected what has been preserved.