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Silverton Alpine Marathon & 50K Course Guide

The Silverton Alpine Marathon & 50K is Aravaipa’s big-altitude San Juan Mountains race, run on the historic Alpine Loop above Silverton, Colorado, and it is defined less by raw climbing than by how high it stays. The whole course lives between 9,318 feet and a 12,930 foot high point on California Pass. I will walk you through the course first, then give you a pacing and fueling plan built for the thin air. There are free calculators along the way to dial in your own numbers.

⏵ At a glance

Silverton Alpine quick facts

Date
Saturday, July 18, 2026
Location
Silverton, Colorado, San Juan Mountains, on the historic Alpine Loop
Distances
50K (about 32 mi), Marathon (about 26.7 mi), and 8 Miler
Elevation gain
50K: about 4,100 ft · Marathon: about 3,800 ft
High / low point
High 12,930 ft on California Pass · low 9,318 ft in Silverton
Start
50K 6:30 AM · Marathon 7:00 AM · 8 Miler 8:00 AM (Silverton Memorial Park)
Cutoff
Checkout cutoffs at California Pass and Gladstone; confirm the exact times with the race
Qualifier
No Western States, UTMB, or Hardrock qualifier status listed by the race

These facts come from the official race site and UltraSignup. Check the current date, start times, cutoffs, and aid stations in the race-day details before you commit. Race logistics change year to year.

The course: where Silverton Alpine is won and lost

The 50K is roughly 32 miles with about 4,100 feet of climbing, run mostly on the old Alpine Loop jeep roads that thread the high San Juans. You pass through mining ghost towns: Howardsville, Eureka, Animas Forks, Gladstone. The marathon shares most of the route at about 26.7 miles and 3,800 feet of gain, and the 50K tacks on an out-and-back to Niagara Gulch. The footing is rugged dirt road, not tight technical single-track, so the difficulty here is the air, not the rocks.

The big climb: up the Alpine Loop to California Pass

The whole day points toward the 12,930 foot high point on California Pass, and that is where the race gets decided. It is a long, grinding climb up the jeep road through old mining country, and the higher you get the less oxygen you have to give. The mistake people make is treating the lower-elevation early miles like a normal trail race and burning matches they cannot spare, then arriving at the pass gassed. Hike the steep pitches up high without guilt. Up there, an honest power-hike often moves you about as fast as a death-march jog and costs you far less.

This is also where the checkout cutoff lives, so the climb is not just a fitness test, it is a clock test. If you go out too easy or stall in the thin air, the high-country cutoff is what ends the day. Get to the top with something left and the rest of the course opens up.

The descents and the rolling jeep road

Once you are over the high passes, a lot of the course is runnable jeep road that rolls and drops back toward Silverton, and it is genuinely fast if you saved something for it. But the surface is loose, rocky dirt road, and long downhill on that stuff still beats up your quads, especially when your legs are already taxed from working hard at altitude. If you trashed yourself on the climb, those rolling later miles turn into a slog instead of the gift they should be.

Practice running loose dirt road and rocky doubletrack downhill before race day, not just buttery single-track. Being able to keep your legs turning over on the descents late, when you are tired and oxygen-starved, is what separates a good day from a long one here.

Altitude, sun, and afternoon storms

Altitude is the thread running through this entire race, and it is the single biggest thing to plan around. Starting at 9,318 feet and climbing to nearly 13,000 feet, your effort will feel maxed at paces that look embarrassingly slow on the watch, and that is just physics, not weakness. If you live low, get to elevation early to adjust, or race off a fresh sea-level arrival before the rough acclimation days set in.

July in the San Juans means strong morning sun up high and a real chance of afternoon thunderstorms rolling over the exposed passes, so there is a reason the gun goes off early. The goal is to be over the high, lightning-prone ground before the weather builds. Carry a layer for cold and wet up top even on a bluebird morning, because the alpine flips fast.

Pacing strategy for a high-altitude jeep-road ultra

With about 4,100 feet of gain and a high point near 13,000 feet, Silverton Alpine is about managing effort in thin air, not hitting a pace chart. Run the climb by feel, and accept that altitude will tax paces that feel easy at sea level.

Pace by grade and effort, not by the watch

Your flat-ground splits mean nothing on the climb to California Pass, and at altitude they mean even less. What matters is grade-adjusted effort, so hold a steady output you can actually keep up the grade and hike the steep, high pitches without fighting it. The classic blowup here is pushing the lower miles because they feel fine, then unraveling near the top when the air runs out. Use a grade-adjusted pace to turn your real fitness into honest climbing and descending targets, then expect to run a notch easier than that on the highest ground because of the thin air.

Build a vert-aware finish prediction

Do not guess your Silverton Alpine finish off a road 50K time. The climbing, the loose jeep-road footing, and especially the altitude all add real minutes, and the altitude penalty is the one most people forget to budget for. A vert-aware finish prediction that accounts for this course’s climbing gives you a realistic window and lets you work backward into the checkout cutoffs at California Pass and Gladstone, so you actually know how much buffer you have at each one instead of hoping.

⏵ Free tools to pace this course

Fueling strategy for altitude and the duration

Most runners are out on the Silverton Alpine 50K for several hours in thin, dry mountain air, and altitude quietly messes with both your appetite and your gut. That makes a rehearsed carbohydrate, sodium, and fluid plan just as important as your fitness.

Carbs: steady, simple, and trained

For a multi-hour effort, aim for somewhere around 60 to 90 grams of carbohydrate per hour, and only push the higher end if your gut is trained for it. Altitude tends to blunt appetite and slow digestion, so favor simple, easy-to-swallow carbs you can get down on autopilot rather than gambling on big, rich late doses your stomach may reject at 12,000 feet. Practice your exact race-day carb rate on long climbs so taking in 70 to 90 grams an hour feels routine, not like an experiment you are running on the worst possible day.

Sodium and fluid: the dry air drinks you

High, dry mountain air pulls water out of you fast, often without the obvious sweat-soaked shirt to warn you, so do not wait until you feel thirsty to drink. A sodium intake in the rough range of 300 to 700 milligrams per liter of fluid works for most runners, leaning higher if you are a heavy or salty sweater. Carry enough fluid to cover the gaps between aid in the high country instead of rationing to the next stop and arriving empty. Weigh yourself before and after a long high-altitude run to find your real sweat rate, then build the plan around your own number, not a generic chart.

⏵ Build your fueling plan

Get a carb, sodium, fluid, and caffeine plan per hour built for your weight, your goal time, and the Silverton Alpine altitude with the free ultra fueling calculator. Browse the rest of the free running tools at the tools hub.

⏵ Train for it with Summit Line

Get a race-day plan built around YOUR fitness, this exact Silverton Alpine course profile, and your projected splits. Summit Line reads your real training, builds a plan for the climbing and the altitude, and rehearses your fueling so race day is something you execute, not guess at.

Start free →Explore the demo

Silverton Alpine Marathon & 50K FAQ

How hard is the Silverton Alpine Marathon & 50K?

It is hard in a way the elevation-gain number does not fully tell you, because the whole thing happens at altitude. The 50K covers about 32 miles with roughly 4,100 feet of climbing, but the course never drops below 9,318 feet and it tops out at 12,930 feet on California Pass, so the thin air is the real difficulty. The footing is mostly historic Alpine Loop jeep road rather than gnarly technical single-track, which sounds friendly until you are gasping at 12,000 feet. If you live near sea level, this race will humble you regardless of your flatland fitness.

How much climbing is in the Silverton Alpine Marathon & 50K?

The 50K has about 4,100 feet of total vertical gain and the marathon has about 3,800 feet, per the official course description. The signature climb takes you up the Alpine Loop toward the 12,930 foot high point on California Pass, and the 50K adds an out-and-back to Niagara Gulch before joining the marathon course. It is not the most vert you will ever see in an ultra, but every foot of it is earned in thin air.

How do I deal with the altitude at Silverton Alpine?

Treat altitude as the headline challenge, not a footnote. The start in Silverton sits at 9,318 feet and the high point is 12,930 feet, so if you live low you should arrive several days early to start adjusting, or come in the day before and race before the worst of it sets in, since the messy middle (roughly days two through four at altitude) is often when people feel the worst. Your pace at 12,000 feet will feel impossibly slow for the effort, and that is normal, so plan to hike the steep, high pitches without fighting it. Hydrate hard in the dry mountain air and do not expect your sea-level paces to mean anything up here.

What are the cutoff times for the Silverton Alpine Marathon & 50K?

The race uses checkout cutoffs at California Pass and Gladstone, so you need to keep moving through the high country to stay in the event. The exact cutoff times shift year to year, so confirm the current numbers in the race-day details before you start. The 50K is the longest of the three distances and has the most generous overall window, but the high-point checkpoint is the one that bites people who go out too easy or stall in the thin air.

What is the terrain and weather like at Silverton Alpine?

The course follows the historic Alpine Loop, a network of old mining jeep roads that link ghost towns like Howardsville, Eureka, Animas Forks, and Gladstone, so the surface is mostly rugged dirt road rather than tight single-track. That makes it more runnable than a typical mountain ultra when your legs and lungs cooperate. Weather is the wild card: July in the San Juans means strong high-altitude sun in the morning and a real chance of afternoon thunderstorms, so you want to be over the high, exposed passes early and you should carry a layer for the cold and the wet.

Is the Silverton Alpine Marathon & 50K a good first ultra?

It can be a stunning goal race, but it is not a gentle place to run your first 50K if you live at sea level. The non-technical jeep-road footing is forgiving, and that is the part that makes it approachable. The altitude is the part that is not, because 32 miles spent between 9,300 and 12,930 feet asks for either real time to acclimate or a smart, patient, hike-the-climbs plan. If you respect the thin air, pace by effort, and arrive early to adjust, a prepared first-timer can absolutely finish and have the day of their life up there.

This guide is independent and for planning only. The course details, dates, start times, cutoffs, and aid stations come from public sources and can change year to year, so confirm the current specifics with the official race before you register or run. The fueling and pacing advice is general and not medical advice.