OBT-3

The OBT-3 is a 338-kilometer long-distance trail in the United States, encircling the Chicago metropolitan area through forest preserves, river corridors, and lakeshore greenways. Gaining roughly 500 meters of elevation over an estimated 20-day thru-hike, this Regional Walking Network route is rated moderate — where cumulative distance and urban navigation matter more than steep terrain, and every stage ends within reach of city convenience.

About the OBT-3

The OBT-3 — part of the Chicago Outerbelt system managed by the Outerbelt Alliance NFP — is one of North America's most distinctive urban long-distance trails. At 338 kilometers (approximately 210 miles), it links 32 mapped sections across Cook, Lake, DuPage, Will, and Kane counties, forming a near-complete ring around one of the continent's great cities.

Unlike wilderness trails defined by remote summits or empty horizons, the OBT-3 offers a mosaic of habitats: old-growth maple canopy, globally significant hemi-marshes, glacially carved river valleys, and Lake Michigan dune ecosystems — punctuated by Chicago's neighborhoods, public art, and legendary food stops. Deer, great blue herons, and migratory songbirds share the route with commuters and casual walkers, giving thru-hikers a sense of life in motion rather than life paused.

The trail is designated as a Regional Walking Network (RWN) route, connecting significant communities and natural areas across the greater Chicago metropolitan region. As covered in a Sierra Club feature on the Chicago Outerbelt, the route represents a genuinely new category in American trail culture: a thru-hike that begins and ends at a world-class urban center. Waymarking is ongoing; GPS navigation remains essential for several sections where signage is incomplete.

Flat by the standards of American long-distance hiking — Illinois's glaciated plains keep gradients gentle throughout — the OBT-3's challenge comes from cumulative distance (338 km), variable surfaces (paved lakefront, gravel paths, muddy forest tracks), and the logistical complexity of moving through a major metropolitan area over multiple weeks. Urban access is also its greatest asset: you are never far from a convenience store, transit stop, or hot meal.

Route Overview & Stages

The OBT-3 is typically hiked as a clockwise loop beginning at Clarence B. Buckingham Memorial Fountain in Grant Park — a symbolic start at the heart of the city. The full 338-kilometer route divides naturally into 12 stages averaging 22–32 kilometers per day, yielding a 19–21 day thru-hike. Experienced hikers may finish in 14–16 days; section hikers often spread the route across 4–6 weekends over a full season.

Highlights & Points of Interest

• Grant Park & Museum Campus — The symbolic start and finish of the OBT-3 places hikers beside the Art Institute of Chicago, the Field Museum, and the Shedd Aquarium, with Lake Michigan stretching to the eastern horizon. Buckingham Memorial Fountain, completed in 1927, is the largest decorative fountain in the world.
• Big Marsh Park — Occupying a reclaimed industrial site in the Calumet corridor, Big Marsh is described by ecologists as a globally significant hemi-marsh. Thousands of migratory waterfowl stop here each spring, and the restored native prairie creates a dramatic contrast to the surrounding industrial landscape.
• Palos Forest Preserve — The most topographically varied section of the route. Kettle moraines, hardwood ravines, and an extensive network of bridle paths create a genuine backcountry feel just 25 km from downtown Chicago. The Little Red Schoolhouse Nature Center, a landmark dating to 1886, serves as a welcome rest stop mid-stage.
• Waterfall Glen Forest Preserve — Encircling Argonne National Laboratory, this 2,430-hectare preserve features a genuine 6-meter waterfall — a remarkable sight in flat Illinois — alongside prairie restoration areas and dense bottomland forest along the Des Plaines River.
• Chicago Botanic Garden & Skokie Lagoons — The North Branch Trail passes through the Botanic Garden's 156-hectare grounds and alongside a 4-kilometer chain of restored glacial lakes. Nesting great blue herons and bald eagles make this one of the route's finest wildlife-watching segments.
• Montrose Point Bird Sanctuary — Known worldwide for its Magic Hedge, a dense hawthorn thicket that concentrates migrating songbirds. In May and September, rare warblers, vireos, and flycatchers gather here in extraordinary numbers — a highlight for any nature-minded thru-hiker passing through Chicago's north lakefront.
• Des Plaines River Trail — One of the longest sustained natural corridors on the OBT-3, this floodplain trail runs for more than 60 kilometers through forest. White-tailed deer, great egrets, river otters, and mink are regularly spotted along this green corridor west of the city.
• Jorgensen Woods — A mature maple-basswood forest section with cathedral-like canopy that turns gold and crimson in late September. The leaf litter here is reputedly among the deepest in the entire Cook County forest preserve system, making autumn hiking especially atmospheric.

Best Time to Hike the OBT-3

The OBT-3 is hikeable year-round, but the Chicago region's continental climate produces significant variation by season. Choosing the right window is one of the most important planning decisions for this route.

Spring (April–May) brings wildflowers and peak bird migration, but river sections can be genuinely muddy after snowmelt and spring rain. Late April is the earliest practical start for a comfortable thru-hike. The first two weeks of May offer Montrose Point at its birding best — warblers peak around May 10–18.

Summer (June–August) provides reliable warmth (average highs of 27–31°C in July), long daylight hours, and mostly dry surfaces. Heat spikes above 35°C are possible in July and August. Carry a minimum of 2 liters of water capacity and expect mosquitoes near wetland sections from June through mid-August.

Autumn (September–October) is the optimal hiking season as of 2026. Daytime temperatures settle between 15 and 22°C, fall foliage peaks across the forest preserves from late September through mid-October, insect activity drops after the first frost, and post-summer trail maintenance leaves surfaces in excellent condition. October is the single best month to hike the OBT-3 — colour, conditions, and comfort align perfectly, and weekend campsites remain available without the summer competition.

Winter (November–March) is feasible for experienced cold-weather hikers on paved lakefront segments, but unpaved forest sections can be icy and treacherous from December through February. All three designated forest preserve campsites close for the winter season, which limits overnight options to urban hotels.

Practical Information

Accommodation

Three dedicated forest preserve camping areas serve the OBT-3, placed roughly evenly around the southern and western arc of the route:

• Camp Bullfrog Lake (Palos Hills) — primitive tent sites, approximately $15–25 per night (approx. €14–23). Advance booking required through the Forest Preserve District of Cook County. Seasonal water and pit toilets on site.
• Camp Shabbona Woods (Calumet region) — individual and group sites from $15–30 per night (approx. €14–28). Pit toilets and seasonal potable water available May through October.
• Camp Sullivan (Oak Forest) — the best-equipped site, with potable water, flush toilets, and a small covered shelter. $20–35 per night (approx. €18–32). The most popular site; book at least 3 months ahead for May–October weekends.

For stages without trail camping, urban proximity is a genuine asset. Budget hotels and short-term rentals are accessible via Chicago's Metra commuter rail network at multiple points along the route. Expect $80–150 per night (approx. €74–139) for suburban Cook and Lake county accommodations. Chicago's transit reach means you can always return to a city base and rejoin the trail the following morning.

Getting There & Back

The OBT-3's Grant Park trailhead is one of the most accessible starts of any long-distance route in North America:

• By air: Chicago O'Hare International Airport (ORD), 30 km from Grant Park, connects to downtown via the CTA Blue Line in approximately 45 minutes (~$2.50 / approx. €2.30). Chicago Midway Airport (MDW), 16 km away, uses the CTA Orange Line (55 minutes, same fare).
• By train: Chicago Union Station and Millennium Station (for Metra Electric) are within 1.5 km of Grant Park. Amtrak's national network serves both, with direct services from Minneapolis, St. Louis, Detroit, and New York.
• By car: Grant Park garages (Millennium Park Garage, Grant Park North Garage) charge from $22 per day (approx. €20). For multi-week logistics, the Metra commuter rail network crosses the OBT-3 at multiple stages, allowing hikers to exit the trail at a station, return to the city overnight, and rejoin the following morning without a second vehicle.

Permits & Fees

No trail permit is required to hike the OBT-3, and all forest preserve sections are free to access. Camping reservations at the three designated sites must be made in advance through the relevant county forest preserve district. Bookings open 6 months ahead of the target date; peak-season (May–October) weekends sell out weeks in advance. There is no fee to download GPS route files or maps from the Outerbelt Alliance — all navigation resources are provided free of charge through their official website.

Gear & Packing List

The OBT-3's flat terrain makes ankle-stiff mountaineering boots unnecessary, but variable surfaces — paved lakefront, gravel paths, muddy river margins, and rooted forest floors — demand a versatile footwear choice. Trail runners with moderate waterproofing perform best across all 12 stages, handling everything from the lakefront asphalt to the seasonal mud of the Des Plaines floodplain.

Pack weight matters significantly on a 20-day thru-hike. For hikers planning frequent urban resupplies every 2–3 days, the Hyperlite Mountain Gear 2400 Windrider keeps the load minimal without sacrificing durability on mixed surfaces. Those planning longer food carries between resupply points benefit from the added capacity of the Osprey Aether 65, which excels at load transfer across the hips — ideal for flat-terrain days where a heavier pack still feels manageable. A well-balanced mid-volume option is the Hyperlite Mountain Gear 3400 Windrider, with enough space for 4–5 days of supplies without the bulk of a full expedition pack.

Key gear considerations for the OBT-3:

• Navigation: GPS device or smartphone with offline maps loaded — waymarking is incomplete on several sections, particularly through urban transition zones between forest preserves
• Insect protection: DEET repellent or permethrin-treated clothing for June through August wetland passages
• Water capacity: 2–3 liters; potable water is available at most urban and suburban stages, but remote forest sections can stretch 8–12 km between reliable sources
• Rain gear: Midwest convective storms arrive fast with little warning — a packable waterproof shell is essential year-round on this route
• Sun protection: Exposed lakefront sections offer little shade during summer months; SPF 50+ sunscreen and a sun hat are important for any June through August hiking
• Food planning: Urban resupply makes carrying more than 3 days of food unnecessary. See our guide to daily hiking calorie needs to budget nutrition for back-to-back high-mileage days on the OBT-3.

For a full kit comparison before you commit to a pack, our ranking of the best ultralight backpacks tested in 2026 covers several models well-suited to the OBT-3's urban resupply model — where a light base weight outweighs volume capacity at almost every stage.

Similar Trails You Might Like

The OBT-3's long-distance, low-elevation character is unusual in North American hiking. If you are drawn to multi-day routes with strong natural highlights and solid infrastructure, these trails offer rewarding alternatives across very different landscapes. For iconic canyon descents in the American Southwest, the South Kaibab Trail and the complementary North Kaibab Trail at Grand Canyon National Park are essential benchmarks. High-elevation Sierra Nevada views await on the Clouds Rest Trail in Yosemite National Park and the nearby Panorama Trail, both offering granite scenery in sharp contrast to the OBT-3's forest and marsh character. For a compact but extraordinary geological experience, Hidden Canyon in Zion National Park delivers slot-canyon drama in a half-day hike. And for hikers looking to build multi-day fitness before committing to the OBT-3, the Theth to Valbona hike in Albania is an outstanding 2-day alpine introduction to back-to-back mountain days.

Frequently Asked Questions

When is the best time to hike the OBT-3?

October is the single best month to hike the OBT-3. Temperatures range from 12 to 20°C during the day, autumn foliage peaks across the forest preserves, mosquito activity ends after the first frost, and post-summer trail maintenance leaves surfaces in excellent condition. Late April through May is a strong second choice for wildflower and bird migration viewing, though muddy river sections after wet periods can slow daily progress significantly.

How difficult is the OBT-3?

The OBT-3 is rated moderate. Its challenge comes from cumulative distance (338 km over roughly 20 days) and urban navigation rather than steep terrain — the Chicago region is almost entirely flat, with a total elevation gain of approximately 500 meters across the full route. GPS navigation is the primary technical skill required, as waymarking remains incomplete on several sections as of 2026.

How many kilometers per day should I plan for the OBT-3?

Most thru-hikers cover 25–32 km per day, completing the full route in 19–21 days. Because the terrain is flat and urban infrastructure is dense, daily distances are highly flexible. Chicago's Metra commuter rail network provides exit and entry points roughly every 20–30 km along much of the route, making it easy to shorten any stage if fatigue or weather demands it without losing your place on the trail.

Where can I sleep along the OBT-3?

Three designated camping areas serve the route: Camp Bullfrog Lake, Camp Shabbona Woods, and Camp Sullivan, with fees of $15–35 per night (approx. €14–32). For stages without trail camping, suburban hotels and short-term rentals are accessible via Metra commuter rail — budget $80–150 per night (approx. €74–139). Advance reservations for the forest preserve campsites are essential between May and October, when sites fill weeks ahead of peak weekends.

Do I need a permit to hike the OBT-3?

No permit is required to walk the trail itself, and all forest preserve sections are free to access. The only fees involved are for overnight camping at the three designated sites ($15–35 per night, booked through the relevant county forest preserve district). The Outerbelt Alliance provides GPS files and detailed route maps free of charge, downloadable directly through their official website before your trip.