136 A HISTORY OF AMERICA IN 100 MAPS
On February 2, 1848, the Treaty of Guadalupe Hidalgo
ended the war with Mexico and extended American
territory to the Pacific Ocean. Just days before the
treaty was signed, a New Jersey carpenter found a
few pieces of gold on the American River in central
California. He shared his discovery discreetly with
the mill’s owner, John Sutter, who tried in vain to
keep the news quiet. After visiting the site, California’s
military commander Richard Mason informed his
superiors that there was enough gold in the country
drained by the Sacramento and San Joaquin rivers
to finance the war with Mexico one hundred times
over. Mason described a frenzied scene, with sailors
deserting their ships, artisans abandoning their shops,
and soldiers leaving their military posts from Sonoma
to Monterey to seek their fortune in the Sierra Nevada
foothills. His breathless report fueled a worldwide lust
for gold that drew thousands to San Francisco.
Mason’s report in the summer of 1848 was
accompanied by this map, one of the first based on
observation rather than speculation. Compiled by
Lieutenant Edward Ord, it depicts the topography
and river system of the Central Valley with a focus on
its mineral resources. The map is centered on Sutter’s
Fort, but describes subsequent gold found to the
north and south and the roads to access each.
It promised even greater riches by locating reports
of gold discoveries along several rivers flowing out
of the Sierra Nevada Mountains to the east.
By focusing on the land and mineral resources,
Ord presented a landscape that was relatively devoid
of human settlement. He marked sites of mines,
mills, and diggings, but made little mention of
Native Americans and others living in the Sacramento
Valley. In this respect the map suggested a vacant
land of abundant wealth, with few obstacles to
development. The topographic and mineral detail
on the map abruptly ends at the peak of the Sierra
Nevada, beyond which knowledge was limited. Ord
GOLD IN CALIFORNIA
E. O. C. Ord, “Topographical Sketch
of the Gold & Quicksilver District of
California, July 25th, 1848”
also shrewdly marked the quicksilver mines near
San Francisco Bay, which by 1851 produced half of
the global supply of mercury, the chemical element
needed to refine gold.
Though the map was made by an agent of the
US military, in both form and content it served as
an invitation to prospecting. Together with Mason’s
report, it was eagerly received by President Polk, who
celebrated the discovery of gold as a sign of American
providence and Manifest Destiny. Victory over Mexico
yielded massive territorial gains, while negotiations
with Britain made Oregon Territory part of the United
States. In the closing months of his presidency, Polk
marveled at this geographical transformation. The
Mississippi River, which had originally marked the
nation’s western boundary, no longer reached even
its midpoint. Polk predicted that California would
soon be as important as the Louisiana Purchase, with
San Francisco Bay rivaling the commercial reach of
New Orleans.
Yet this territorial growth also brought serious
strains. Conflicts with Indian tribes in California and
elsewhere in the West reminded the president that this
land had long been inhabited. Even more urgent were
the political concerns that slavery might extend into
California. The president dismissed these by arguing
that the climate and soil of the West would never
support large-scale agriculture. But he also defended
the interests of slaveholders by acknowledging and
validating the state rights arguments that had begun
to emerge in the South. Polk proposed to settle the
crisis by extending the Missouri Compromise line—
which divided free from slave territories along the
36 ° 30' parallel—to the Pacific. Instead, arguments
over the fate of these new territories raged until a
series of compromises strengthened protections for
slavery in the South in exchange for the admission of
California as a free state.
In a larger sense, the timing of these events
demonstrates that there was nothing providential
about the expansion of the United States between
1803 and 1848; rather, these territorial gains came
through purchase, negotiation, military force,
and—in the case of the California gold fields—
extraordinary good fortune.