Midewin National Tallgrass Prairie's Block 61 Trail

Block 61 at Midewin National Tallgrass Prairie has a rare quality that I'm always seemingly chasing: the feeling that something important used to be here… and that the land is still deciding what to do with it.

Midewin National Tallgrass Prairie is a federally protected prairie reserve near Wilmington, Illinois, managed by the U.S. Forest Service. Established in 1996, it is the first national tallgrass prairie in the United States and serves as a major ecological restoration project on former Joliet Army Ammunition Plant land, which served the war efforts of both World War II and the Vietnam War. The name chosen was “Midewin,” derived from the Potawatomi word referring to a traditional society or gathering of healers.

Today's blog focuses on the Block 61 trail to the east; which in many spots feels less like a nature hike and more like an archaeological survey of the Cold War.

Men only want one thing. The thing:

Step inside and the temperature drops. Sound flattens. The curved ceiling amplifies the sense of containment. Two simple benches sit against the wall, modern additions that invite reflection.

In 1940, as war consumed Europe and American neutrality grew increasingly fragile, the federal government began assembling land southwest of Chicago for a new industrial complex: the Joliet Army Ammunition Plant.

The Block 61 Trail in Yellow; the trail itself is not over any abandoned railroad lines, and uses internal Plant roads that were adjacent to the rail lines which served the bunkers.

Longtime readers of this blog will remember that we've visited the area previously, checking out the Henslow Trail, which serves as one of the trails, utilizing an abandoned railroad line and bridge over Route 53 that transported munitions between the eastern and western areas of the Ammunition plant. In the above map, the Henslow Trail is the bridge over route 53 in the southwesternmost portion of the map.

PBS created a documentary of the transformation of the Joliet Arsenal from arsenal to tallgrass prairie which I highly recommend. 

The point I made last time about I Can See For Miles is even more poignant in the late Winter.

The site eventually encompassed roughly 23,500 acres across Will County. It was not chosen accidentally. The area offered rail access, relative isolation from dense urban neighborhoods, and sufficient land to create buffer zones between explosive operations.

Restoration began with a difficult reality: this was not pristine prairie waiting to be revealed. It was a working industrial landscape with altered hydrology, compacted soils, invasive species, and buried infrastructure. Prairie restoration here is not nostalgia, but still active reconstruction. Native grasses and forbs have been reseeded. Controlled burns are conducted regularly. Bison were reintroduced in 2015, reestablishing a keystone species that once shaped these ecosystems through grazing patterns.

Coldwater Rd

The Block 61 area occupies the east side of the Midewin property; where TNT was assembled into components that would finish the weapons. As I've already documented the Iron Bridge (Henslow Trail); maybe one day I will finish this with a trilogy where I discuss the west side of the Plant.

The Plant was not a single factory but a vast, decentralized network of production areas, storage bunkers, test facilities, rail spurs, internal roads, and protective berms. The complex was designed with spacing as a safety feature: if one building detonated, the blast would (in theory) be contained.

I say in theory, because in 1942, shortly after the plant came online, "an explosion took place in a loading line at a plant Building 10. Workers had been loading anti-tank pressure minds into railroad cars. Whatever happened next set off three railroad cars loaded with the weapons, an explosive weight equal to approximately 62,600 lbs. of TNT. The blast shattered windows for miles around and was allegedly heard in Waukegan, close to 100 miles away. The 48 killed made it the deadliest US ammunition plant incident of World War II." (University of Illinois Press)

As you can no doubt tell, the trail is relatively flat and easy to navigate, and best visited in fall or winter if you want clear views of the concrete remnants. That said, do bring waterproof footwear after rain, as drainage patterns from the old site still influence ground conditions.

The easternmost bunkers. From this vantagepoint, its quite easy to tell that they were served by rail.

Several of the bunkers were open for exploration, although there was little to be discovered inside, sans nostalgia for the Cold War era. 

The Block 61 loop is roughly three miles, and while the seemingly endless bunkers along the road get repetitive after awhile, I'm glad that so many were preserved; it really helps to tell the story of how large this place really is, and how much land was used in the development of weapons and munitions for the war effort, for both better and worse.

This isn't Grant Creek, but it's a good time to bring up the ecological impact of the Plant." While the arsenal was active, water in Grant Creek ran red. The creek was heavily disturbed by contaminants from the TNT manufacturing process. Grant Creek has recovered and exhibits the highest biological diversity on the property. Because the majority of its watershed is in grasslands, the creek receives very little runoff and silt from crop fields." (US Forest Service)

The area was undergoing restoration work during my visit, removing invasive weeds and promoting a return to wild prairie after two centuries of agriculture and quite a few decades of ordnance development and testing.

Block 61 is not picturesque in the traditional sense. It is transitional. The trees are still leafless in winter. The ground is patchy with moss and mud. The foundations interrupt what would otherwise be uninterrupted grassland. But that interruption is the point.

A sign explaining the next stage of restoration on the property: Midewin’s primary mission is to restore native tallgrass prairie ecosystems once common across the Midwest. Restoration efforts involve reintroducing native grasses, wildflowers, and wildlife, controlling invasive species, and rehabilitating soil and hydrological conditions altered by decades of industrial use. The site represents one of the largest prairie restoration projects in North America.

The land required extensive environmental remediation. Decades of explosives manufacturing left contamination concerns ranging from TNT residues to heavy metals. Cleanup efforts were complex and politically fraught. Local governments, federal agencies, and community groups debated the site’s future.

Several thousand acres were transferred for industrial redevelopment, eventually becoming the CenterPoint Intermodal Center, which is now one of the largest inland ports in North America.

More ruins to visit at the entrance to the trail; I don't think this was a bunker, but there was no indication as to what was previously here.

Thanks as always for reading!