The Quicksilver Endurance Runs roll back into Almaden Quicksilver County Park on the southern edge of San Jose on Saturday, marking the 41st edition of one of the longest-running ultramarathons on the West Coast. Saturday's programme features a 100K and a 50K, both rolling out from the Hacienda Entrance, with the 100K beginning at 4:30 a.m. and the 50K following at 7 a.m. The races are organised by the Quicksilver Running Club, which has stewarded the event since 1985 and helped seed a generation of California ultrarunners on these former mercury-mining trails.
Attention this year is squarely on the 100K, the twelfth edition of the longer distance and a designated Western States Endurance Run qualifier. Finishers have 17 hours to negotiate the roughly 13,000 feet of climbing across a mix of fire roads and singletrack to bank a 2027 Western States lottery ticket. The course rolls south from the trailhead before threading parkland that overlooks the Santa Clara Valley, with Sierra Azul ridges visible on the longer climbs. Conditions are typically warm by mid-morning, and aid stations stocked by the host club are spaced to keep runners moving rather than lingering.
The 50K runs concurrently and counts as a Pacific Association/USATF Ultra Grand Prix scoring race, which has historically drawn a sharp Bay Area field. Runners have nine hours to complete the loop, which packs more than 6,000 feet of vertical into a course that shares much of its character with the 100K but trims the longest out-and-back legs. Grand Prix points have decided several recent regional standings on the final lap of races like this one, and a strong day at Quicksilver can rearrange the championship table heading into summer.
Beyond the elite hunt, the event remains a community fixture. The Quicksilver Running Club fields a deep volunteer roster, and aid station crews include alumni who have run the race themselves multiple times over the decades. The trails were once used by the New Almaden mercury miners whose rusted equipment still dots the park, and race director updates this week confirmed that recent trailwork crews have cleared key sections of the Mine Hill and Wood Road climbs after a wet spring. Both distances have been at or near capacity in recent years, and the field on Saturday again features a strong representation of Northern California clubs.
For runners using Saturday as a stepping stone, the long view is what matters. A clean Quicksilver 100K finish puts a name into the December Western States lottery, joining graduates from the Black Canyon, Canyons and Bandera ticket races already pencilled in. For the 50K field it is a more immediate scoreboard, with Grand Prix series leaders looking to either consolidate or wrest the lead in a season that runs deep into autumn. Either way, by Saturday evening the Hacienda finish chute will have once again served as the meeting point of one of California's most enduring ultrarunning communities.