It’s not every day you come across a half marathon that rolls out a red carpet—or in this case, a smooth, crushed-stone trail—through a historic rail corridor, all while raising money for the land trust that keeps it beautiful. The Black Diamond Express Half Marathon & 5K on Sunday, August 23, 2026 in Mendon, New York, is that race. Flat, fast, and full of charm, this event might just be the low-key gem you’ve been looking for.
The Course: Flat, Fast, and Paved with History
The course runs along the Lehigh Valley Trail, a multi-use trail that follows the route of the old Lehigh Valley Railroad. Out-and-back from the Mendon Youth Baseball Fields, the surface is mostly crushed stone and packed dirt—stable enough for road shoes, soft enough to feel kind on the legs. The official description: flat. No hills to speak of. That makes it a prime candidate for a personal best, especially if you’ve been grinding on rolling roads all season.
The half marathon is USATF certified (NY17052JG), so if you’re chasing a time that counts, this one checks the box. Recent resurfacing on sections of the trail only sweetens the deal. The 5K starts twenty minutes after the half, making it an easy add-on for a friend, family member, or a tune-up for your own legs.
The Experience: Low-Key, High-Touch
Part of what makes the Black Diamond Express special is its size and heart. The race benefits the Mendon Foundation, the local land trust that preserves and maintains the Lehigh Valley Trail in partnership with Monroe County Parks. You’re not just running—you’re supporting the trail beneath your feet.
Perks: the first 150 entrants (combined half and 5K) who register by August 2nd get a choice between a long-sleeved unisex t-shirt or a mug. After that, shirt sizes are first-come, first-served until they’re gone. Finishers in the half receive a ceramic medal, and 5K finishers get a ceramic lapel pin. These aren’t your typical stamped medals; they have a collectible, handcrafted feel that stands out on any display.
Start and finish are at the Mendon Youth Baseball Fields, with plenty of parking, and post-race refreshments and healthy snacks. The vibe is community-run, cheerful, and focused on making the experience enjoyable—not just for the front of the pack, but for everyone.
Who This Race Is For
First-timers: If you’ve never tackled a trail half marathon, this is a fantastic introduction. “Trail” can sound intimidating, but this course is flat and smooth—more like an unpaved bike path than a technical mountain singletrack. You won’t need trail shoes unless it’s rained heavily. The out-and-back format means you’re never far from the start/finish energy, and the small field makes for a less overwhelming atmosphere.
PR-seekers: Flat + USATF certified + good surface = PR territory. The Black Diamond Express quality score of 72 out of 100 makes it a Standout race among half marathons, with favorable conditions for a fast time. Late August weather in Mendon typically sees a high around 78°F and a low near 62°F—cooler if you get an early start. The 8:00 AM start helps beat the heat.
50-state chasers: New York is a popular state to check off, and this race offers the charm of a small-town event without a huge travel burden. Plus, if your schedule doesn’t allow for live racing in August, there’s a virtual option that lets you complete the distance within a week of race day and still earn the shirt/mug and medal (subject to availability after the live race).
Logistics and Weather: What to Know
- Date: Sunday, August 23, 2026
- Location: Mendon Youth Baseball Fields, Mendon, NY (Google Maps pin available on the race page)
- Half marathon start: 8:00 AM | 5K start: 8:20 AM
- Weather: Typical highs in the upper 70s, lows around 62°F. August in upstate New York can be warm and humid—plan for hydration and sun protection. The shaded trail sections help.
- Virtual option: Complete your race within a week after August 23 and receive your swag by mail.
- Swag guarantee: For the first 150 registered by August 2nd. After that, supplies are limited.
This is the kind of race that reminds you why you run: a beautiful place, a supportive community, and a tangible reward at the finish. Whether you’re after a PR, a new state, or just a lovely summer morning on a historic trail, the Black Diamond Express is worth the trip.
Ready to sign up? Head over to the Black Diamond Express Half Marathon & 5K race page for full details and registration.