Mt. Si Relay

Want to try your first relay race? How about a relay that won’t keep you up all night? The Mt. Si Marathon Relay is great for first-timers, as well as for seasoned teams seeking a fun event without too many logistics. There are five people per team, with each team member running two legs of 3-8 miles. Your team of five can ride in one vehicle. Team categories are determined by total team age on race day, which allows flexibility in assembling your team.

Most of the 60-mile course is on the hard-packed Snoqualmie Valley Trail. The trail’s gentle grade is excellent for running with spectacular views. Exchanges are well-marked and manned by volunteers. Method of exchange is a simple touch off by hand.

For detailed relay information, see our Relay page.


As with the relay, the ultra events are excellent venues for runners stepping up to a 50K or 50-mile distance for the first time. The trail is generally smooth without too much elevation, with very good support on the course.

For 50-milers there are 12 full aid stations. For 50K participants, there are 9 full aid stations. Of course everything that makes the ultras good for first-timers also makes it a fast and rewarding adventure for experienced ultra runners.

Categories are Open (under 40) and Masters (40+), for both men and women.

For detailed ultra information, see our Ultras page.

Half Marathon and Marathon

The half marathon and marathon distances are good options for those that want to run the race but do not want to run a full ultra distance. The trail is generally smooth without too much elevation, with very good support on the course.

For half marathon participants, there are 6 full aid stations along the course. For marathon participants, there are 8 full aid stations along the course.

Categories are Open (under 40) and Masters (40+) for both men and women.

For detailed information, visit our half marathon page and marathon page.

Packet Pickup

Packet pickup will be Saturday, April 23, from noon to 4 p.m. at Plateau Runner,
1490 Northwest Gilman Blvd, Suite J3, Issaquah, WA 98027. 425-898-4173

Packets will include race shirts, numbers and pins.

To limit paper waste, packets will NOT include driving directions, printed course descriptions, maps etc. We encourage runners to print necessary information from this website.

NOTE: Runners not showing up will forfeit their entry fees. Packet pickup is also available on race day near the starting line. Please arrive early if you choose this option.

Finish line

Refreshments will be available at the finish area. A limited number of shirts from this year and previous years will be for sale.

Results and awards

Results will be available as soon as possible after the race on this website’s results page. Awards will be given to the top finishers in each category/division. All finishers receive a unique Mt. Si Ultra medal. Awards not picked up at the event will be mailed. Direct any questions to

Event history

The event began as the “Falls to Gasworks Relay” in 1983, beginning at Mt. Si High School near Snoqualmie Falls and ending at Gasworks Park in Seattle. In 1999, the event was moved to the Snoqualmie Valley and was renamed the Mt. Si. Relay & Ultra Run. In 1999 the solo run was 52.1 miles, and in 2000 it was changed to a 50.0 miles. In 2003, a 50K solo run was added and the name was changed to Mt. Si Relay & Ultra Runs.

In 2017 we started adding shorter distances, having a 25K in 2017, a half marathon and 20-Miler in 2018, a 5-Miler, half marathon and marathon virtually in 2021 and the current distances of a half marathon and marathon for our 2022 race. Due to COVID, we had to cancel our 2020 race. With adding the shorter distances, we changed the name to Mt. Si Relay & Trails Runs.