California had been a state for scarcely a decade and was home to fewer than 500,000 people when it was hammered in the winter of 1861-62 by the most powerful series of rainstorms in recorded history.

“This event, which was characterized by weeks-long sequences of winter storms, produced widespread catastrophic flooding across virtually all of California’s lowlands — transforming the interior Sacramento and San Joaquin valleys into a temporary but vast inland sea nearly 300 miles in length and inundating much of the now densely populated coastal plain in present-day Los Angeles and Orange counties.”