In 1886, the South Pacific Coast Railroad started building a branch line from the mainline at Campbell, CA to service the quicksilver mines at New Almaden, south of San Jose. Not to be outdone, neighboring Southern Pacific decided to build a branch from their own mainline at a location called Seven Trees in order to access the same quicksilver mines. This branch line became known as the New Almaden Branch, and was officially opened in November of 1886, just four months after the SPC opened their adjacent line; SP terminated the New Almaden Branch in Almaden Springs at a passenger depot located at the intersection of present-day McKean and Cahen Roads. The end of the line was yet two miles away from the quicksilver mines due to the narrow canyon at the mine's entrance.
The New Almaden Branch saw regular service handling incoming shipments to the mine; it also carried the daily Almaden Express passenger train from San Jose. It also included a spur track to the Goodrich Quarry at Greystone to transport sandstone that was used in the construction of many important buildings, including many at Stanford University, San Jose's post office, hall of justice, and St. Mary's Church, as well as several SP depots.
In 1906, SP opened Sunset Park, at what is now the current site of Almaden Lake Park near Coleman Road and Almaden Expressway. Picnic trains from San Francisco operated on Sundays and holidays until World War I, when the trains gave way to the rising use of automobiles. By 1922 service on the branch had declined to a single train on Mondays, going from Campbell to New Almaden (over the former SPC trackage) and then back up the New Almaden Branch to a location named Lick. In 1934, portions of the branch were abandoned when the mines shut down during the Great Depression. The remaining 3.6 miles of the branch from Lick to Alamitos was abandoned in the early 1940s, but the booming economy brought it back to life, and it was re-named the Lick Branch.