⏵ Course guide · Mississippi River bluff loop
The Mines of Spain 100 repeats a roughly 20-mile loop through Louis Murphy Park and the Mines of Spain Recreation Area in Dubuque, Iowa, about 14,000 feet of gain, Mississippi River views, and a 33 hour clock. The race calls itself perfect for your first hundred or your hundredth. I will walk you through the loop and aid layout first, then give you a pacing and fueling plan built for mixed technical-to-rolling terrain, plus free tools to dial in your own numbers.
These facts come from the official Mines of Spain 100 race information page. Crew, pacer, and cutoff rules are enforced strictly, so confirm the current specifics on minesofspain100.com before you commit.
Both the 100 mile and 100K run the same roughly 20-mile loop starting and finishing at Louis Murphy Park, spending most of its distance inside the Mines of Spain Recreation Area with views of the Mississippi River and the iconic Horseshoe Bluff.
Each lap moves through steep and technical sections, flat dirt singletrack, and rolling grassy trail, with a couple of short paved stretches connecting the different parts of the course. That variety means you rarely settle into one rhythm for long, which the race itself frames as a strength: something for every kind of runner in the same loop.
Crew access is limited to exactly two points: the Start/Finish at Louis Murphy Park and AS#3 at EB Lyons. That is a deliberate choice, the race runs overnight in a park with limited parking and closed to the public after hours, and the organizers take violations seriously enough to disqualify runners over it. Plan your crew logistics around those two stops from the start.
About 14,000 feet of gain for the 100 mile comes entirely from repeating the same roughly 20-mile loop five times. By your final lap you will know exactly where every climb sits, which cuts both ways: no surprises, but also no relief from the sections that wore you down the first four times through.
With a 33 hour cutoff and an intermediate checkpoint requiring you to start your final loop by 11:00 am Saturday, this course gives you clear checkpoints to gauge your pace against.
Because each loop swings between steep technical sections and flat, rolling trail, a single flat-ground pace target will not serve you well here. A grade-adjusted pace target for the loop, applied consistently across all five laps, gives you an honest number for what effort is sustainable over 100 miles of this terrain.
The 100 mile requires starting loop 5 by 11:00 am Saturday, well before the overall 5:00 pm finish cutoff. A vert-aware finish prediction built off your first two or three loops, checked against that intermediate cutoff rather than just the finish line time, tells you honestly whether you are on pace with enough runway left to adjust.
⏵ Free tools to pace this course
A Friday 8:00 am start and a 33 hour cutoff mean most 100 mile finishers spend a full day, a full night, and part of a second day out, through eastern Iowa weather that historically ranges from the upper-30s to the low 60s.
Aim for roughly 60 to 90 grams of carbohydrate per hour. Even though you pass through the 4 aid stations a total of 5 times per loop, crew can only reach you at the Start/Finish and AS#3, so rely on drop bags and race-provided aid at the other stations rather than assuming crew support everywhere.
Sodium in the 300 to 700 mg per liter range covers most runners here. Given the historical lows in the upper 30s to low 40s overnight, prepare for both a warmer daytime effort and a genuinely cold night, adjusting your sodium and layering plan accordingly rather than assuming stable conditions all race.
⏵ Build your fueling plan
Get a carb, sodium, fluid, and caffeine plan per hour built for your weight, your goal time, and a cool mid-October eastern Iowa day and night 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 mixed technical-to-rolling loop profile, and your projected splits. Summit Line reads your real training, builds a plan for repeated loop racing, and rehearses your fueling so race day is something you execute, not guess at.
Mines of Spain 100 is a genuinely well-rounded ultra: the race's own description calls it "perfect for your 1st hundred or your 100th hundred." A roughly 20-mile loop repeats five times for the 100 mile distance, climbing about 14,000 feet total through terrain that ranges from steep and technical to flat dirt singletrack to rolling grassy sections, with views of the Mississippi River and the iconic Horseshoe Bluff along the way. The 33 hour cutoff gives a well-prepared runner real margin, and strict rules around crew and pacer access, only at the start/finish and AS#3 EB Lyons, keep the race fair and manageable for the organizers running it inside an active park.
The official race site lists about 14,000 feet of gain (and 14,000 feet of loss) for the 100 mile distance, and about 8,400 feet of gain and loss for the 100K. That climbing comes from five repeats of the same roughly 20-mile loop, so you get intimately familiar with every hill by your final lap.
With an 8:00 am Friday start and a 33 hour cutoff, plan for a full day, a full night, and well into a second day. Aid stations sit 2.1 to 6.3 miles apart and you pass through 4 of them a total of 5 times per loop, giving frequent chances to refuel, though NO aid is allowed from crew outside the two designated crew-accessible stations (Start/Finish and AS#3 EB Lyons). Aim for roughly 60 to 90 grams of carbohydrate per hour, and sodium in the 300 to 700 mg per liter range, adjusting for mid-October eastern Iowa weather that historically ranges from upper-30s/lower-40s lows to upper-50s/lower-60s highs. Build your numbers with the free ultra fueling calculator before race day.
The 100 mile cutoff is 33 hours, with the finish line closing at 5:00 pm Saturday from an 8:00 am Friday start. There is also an intermediate cutoff: you must start your 5th loop by 11:00 am Saturday. The 100K cutoff is 23 hours, finish line closing at 7:00 am Saturday, with an intermediate cutoff to start the 3rd loop by midnight. Runners 60 or older can request a 7:00 am early start for the 100 mile only, which must be arranged by Thursday of race week.
Crew access is strictly limited to two spots: the Start/Finish at Louis Murphy Park and AS#3 at EB Lyons. No aid is permitted from crew anywhere else on course, including caching, and violations are grounds for disqualification. Pacers are allowed for the 100 mile after 3 loops (or after 2 loops if you begin loop 3 after 7:00 pm), and for the 100K after 2 loops, one pacer at a time, with pacer access also limited to those same two crew-accessible points.
Yes, and the race markets itself directly to first-timers: "perfect for your 1st hundred or your 100th hundred." The loop format means you return to Louis Murphy Park regularly, simplifying crew logistics and giving you a mental landmark every lap. The mixed terrain, technical in places but with plenty of flat and rolling sections too, gives a first-time hundred mile runner a genuine but fair test, and the 33 hour cutoff leaves real room for a well-trained but conservative pace.
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<a href="https://runsummitline.com/guides/mines-of-spain-100">The Mines of Spain 100 course guide</a><iframe src="https://runsummitline.com/embed/race/mines-of-spain-100" style="width:100%;max-width:420px;height:180px;border:0;" loading="lazy" title="Mines of Spain 100 course guide by Summit Line"></iframe>This guide is independent and for planning only. The course details, dates, 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.