The South Pacific Coast Railroad built the mole between 1876 and 1878 as the northern terminus of its narrow-gauge line to Santa Cruz. The logic was geographic: Alameda's western shore faced San Francisco across the bay, but the water between them was too shallow for ferries to approach the shoreline. The solution was to build out -- a long causeway extending tracks into navigable depth. Southern Pacific leased the mole in 1887 and expanded its reach. When the structure burned to the waterline on November 20, 1902, they rebuilt it larger and farther into the bay. By 1898, the mole carried both narrow and standard gauge tracks; after the 1906 earthquake, it converted entirely to standard gauge. This was infrastructure shaped by the stubborn physics of San Francisco Bay -- its tidal mud flats demanded that builders meet the water where it was deep enough to cooperate.

At its peak, the Alameda Mole served as an improbable intersection of transit modes. Local trolley cars on the Red Line terminated here. Ferries departed for San Francisco. Regular trains ran in a horseshoe pattern -- the aptly named Horseshoe Line -- connecting to the Oakland Mole farther north. Southern Pacific's electrified commuter trains, full-sized railroad cars rather than streetcars, crossed to the mainland on bridges at Webster Street and Fruitvale. The mole was one of four neighboring piers serving the same purpose: the Oakland Mole, the Western Pacific Mole, and the Key System Mole all pushed their own tracks across the mud flats into ferry-accessible water. Standing on any one of them, you could look across the shallows and see the others, a constellation of transit ambition driven into the bay on timber and stone.

In the 1930s, the fill leading to the Alameda Mole found a new tenant. Pan American Airways established a seaplane port along the causeway, and this unlikely stretch of East Bay reclamation became the original home base of the China Clipper. The great flying boats departed from here on their transpacific routes, carrying mail and passengers to Hawaii, Midway, and Manila. When World War II arrived, the military recognized what the railroads had known for decades: this was prime waterfront. The marshy lowlands southwest of the mole were filled on a massive scale, and Naval Air Station Alameda rose on the reclaimed ground. The facility grew to include a major airfield and docks capable of berthing aircraft carriers. For more than half a century, the naval station dominated the western end of Alameda, a military city built on the same mud flats the railroads had once struggled to cross. NAS Alameda closed in 1997, leaving behind hundreds of acres of former military land still being reimagined.

Ferry service from the Alameda Mole ended in 1939. The cause was visible from the mole itself: the San Francisco-Oakland Bay Bridge, which opened in 1936, rendered the ferry system obsolete almost overnight. All transbay service was rerouted across the new bridge. For passengers in Alameda, the change was particularly inconvenient. The island city had no direct bridge access, so commuters now had to travel outbound across the Fruitvale Bridge into Oakland before looping back toward San Francisco on the Bay Bridge -- a longer, more circuitous journey than the direct ferry crossing had been. The mole itself passed into the expanding naval station. Today, almost nothing of the original structure remains visible. The pilings and platforms that once bustled with ferry passengers, trolley riders, and railroad commuters have been absorbed into the landscape of the former NAS Alameda, where redevelopment projects are slowly transforming the old military base into housing and commercial space. The mud flats are still there, though, just beneath the surface.