Arsenal Days Preview

In 1982, a man named Carl heard the call of the upland sandpiper. The common call is a series of pipping notes of the same pitch given while in flight. There is a distinctive song of males displaying for females on spring nights. It begins with an ascending trill, ending in a pure tone of a “wolf whistle”. And it sounds like this... Carl was at the Joliet Army Ammunition Plant. This might not seem important in the whole scheme of things. Except, this bird was on the endangered species list.

Carl N. Becker was uniquely qualified to identify the upland sandpiper. He was Illinois’ first Endangered Species Coordinator. He knew that these birds required large pasture sizes and short grass height provided by grazing cattle. The Joliet Arsenal had this. It provided a perfect breeding habitat for the upland sandpiper. These factors may have drawn Carl to investigate the Arsenal in hopes of finding such a species.

In 1983, the discovery of the upland sandpiper encouraged the IDNR, Illinois Department of Natural Resources, to seek Army permission to conduct upland sandpiper surveys on 6,000 acres of Arsenal pastureland. These tracts of grassland habitat grazed by cattle were the largest still existing in Illinois. The survey confirmed Carl’s suspicion. The Arsenal grasslands contained the largest population of endangered upland sandpiper in Illinois.

The survey also uncovered the largest population of endangered loggerhead shrike in Illinois. Additionally, other birds in decline were found on the Arsenal pastures. The species included the Henslow sparrow, grasshopper sparrow, meadow lark, bobolink, and dickcissel. These birds are considered “area sensitive” and require large acres of grassland to breed successfully.

1991 saw the future of the Joliet Arsenal in question . It was listed as a Superfund Site. These sites are polluted locations in the United States requiring a long-term response to clean up hazardous material contaminations. This was due to the use of the Arsenal land to produce munitions and TNT since 1940. The Department of Defense decided, in 1992, to surplus the Arsenal. This meant the disposal of 23,500 acres of Arsenal land but this was NOT a considered a base closure. This gave the state of Illinois the right to purchase the property. That is if other federal agencies declined accepting the property for other federal purposes. At the time, the value of the 23,500 acres was estimated at $23.6 billion.

By 1993, the IDNR had 11 years of grassland bird data from the annual surveys. This data was critical in persuading then Governor Jim Edgar to save the Arsenal lands for wildlife habitat and open space in Illinois. The importance of this project to Illinois was seen as Governor Edgar assigned Al GrosbolI, from his staff, to act as policy lead. Fran Harty, with 12 years’ experience as a IDNR Natural Heritage Biologist on the Arsenal project, volunteered to work as the IDNR’s point person. He later became senior director of special projects for The Nature Conservancy and stayed involved with Midewin through a partnership with The Nature Conservancy.

In that same year, U.S. Army Colonel Alan Kruse convened the re-use plan for the Arsenal. He wanted to know the location of endangered species on Arsenal land. The Army provided $35,000 for a survey of the 23,500 acres of Arsenal land and the adjacent 4,000 acres of the Joliet Army Training Area. They goal was to determine the exact location of threatened and endangered species. The Nature Conservancy & the IDNR managed the funds and hired contractors to survey avian, botanical, reptile & amphibian, and insect species. Survey results showed 16 threatened and endangered species that called this land home on an annual basis for breeding, wintering, and foraging. Eleven of the species were birds.

In 1994, the IDNR National Heritage Biologist, Bill Glass wrote a report of the survey. The report included maps showing the habitats and boundaries of each species. These maps later served as the basis for the division of the 23,500 acres of Arsenal land. It was divided into 19,500 acres for Midewin, 50 acres for a county landfill, 3.000 acres for two industrial parks, and 950 acres for the Abraham Lincoln National Cemetery. Bill Glass later became the first ecologist for Midewin National Tallgrass Prairie.

The goal was still for the state of Illinois to eventually purchase the land. A strong local and state partnership was formed by pulling together key Illinois and a few national conservation organizations. This resulted in full bipartisan support from Illinois congressional delegates. A federal partner was still needed to receive the Arsenal property in the chain of disposal before it could be purchased at the state level. It was thought that the U.S. Fish & Wildlife Service would be the federal partner but due to fiscal restraints they pulled out. The U.S. Forest Service became interested due to efforts of Dr. Larry Stritch, botanist of the Shawnee National Forest in southern Illinois and later Forest Service National Botanist.

Between 1994 and 1996 several things occurred. U.S. Illinois Congressman, George Sangmeister, formed a 24-member Joliet Arsenal Citizen Planning Commission. Illinois Governor Edgar created the 19-member Joliet Arsenal Governor’s Coordinating Council. The Chicago Tribune newspaper wrote 14 editorials in support of saving the Joliet Arsenal for open space, wildlife habitat, and the creation of America’s first National Tallgrass Prairie. There was a patchwork of people, conservation organizations, and politicians that wanted the Arsenal lands to remain open for habitat of these unique animal and plant species. On April 8, 1994, the 24-member Joliet Arsenal Citizen Planning Commission voted unanimously to adopt a land use concept plan for the Arsenal. The land use plan was the same map from the Endangered Species Report prepared by Bill Glass.

In 1994, Congressman Sangmeister, a democrat, introduced a bill to congress to adopt the re-use plan and transfer the Arsenal from Army to the U.S. Forest Service. This bill did not get called to vote and Sangmeister retired. In 1995, Congressman Jerry Weller, a republican, won Sangmeister’s seat and took up the effort to pass the bill. On the Senate side, Illinois Senator Paul Simon inserted this bill, the “Illinois Land Conservation Act of 1995” into the National Defense Authorization Act for Fiscal Year 1996. The bill passed Congress on January 3, 1996. On February 1, 1996, the law was signed into effect transforming the Joliet Arsenal into Midewin, America’s first National Tallgrass Prairie.

It is amazing to think that 19,500 acres will one day be a mosaic of tallgrass prairie and grassland pastures that once covered Illinois. Many people and groups have been involved and continue to partner and provide funding to make this goal reachable. It will take decades to see the seeds of this project reach fruition. Every piece of unwanted Arsenal infrastructure taken out, invasive species controlled, native seeds germinating in bison tracks, and grassland birds nesting by the thousands in grassland pastures grazed by bison and cattle all bring us closer. Nearer to the dream so many folks have seen and worked to create since Midewin was signed into existence in 1996. The dream of once again seeing a landscape covered with tallgrass prairie and grassland birds.

All this happened because a man knew the call of the upland sandpiper and did something about it.

Turning off Illinois Route 53 into the Iron Bridge Trailhead you are at the crossroads of thousands of years of regional history, if you know what to look for! The entrance road is actually a segment of old Blodgett Road, used from the mid-Nineteenth Century until the Army bought the land in 1940. It divided Jackson Township on the north from Florence Township on the south. Since one of the functions of township government in Illinois was the building and maintenance of roads, township roads were important since the cost of building and maintenance could be shared by the two townships they joined.

The railroad tracks along the west side of Route 53 run in the same rail bed laid for the Chicago, Alton, and St. Louis Railroad in 1854. Just after midnight on the third of May, 1865, the train bearing the body of President Abraham Lincoln passed over the old Blodgett Road crossing, on the way from Chicago to Springfield for final interment. Illinois Route 53 didn’t exist at the time.

In 1922, the road, initially called simply, “the concrete road” was built along the east side of the railroad tracks, between Hoff Road on the north and a point about a mile south of here where it merged into the north-south running township road. In 1926, what are now the two southbound lanes were incorporated into the original Route 66. Sometime after 1940 the Army had the road expanded to four lanes to carry additional arsenal traffic. At that time, it was re-designated, “Alternate” Route 66.

The restored prairie on the south side of old Blodgett looks much as it would have six thousand years ago when the tallgrass prairie became the dominant ecosystem, until the arrival of Euro-American farmers in the 1830s. A prehistoric Native American site dating from the Middle Woodland period about 2,000 years ago lies under a small portion of this prairie. The wooded area to the north shelters the remnants of the Moses Morgan farmstead. Morgan arrived in Kendall County, Illinois from New York in the late 1840s. He moved to this site in 1855. Foundations of the house, barn, and other farm buildings are still visible on the ground there, and trees planted by him and his descendants still grow here. Morgan prospered, and his family grew. By his death in 1878 he owned 13 local farms and when the Army purchased the land in 1940, the Morgan family owned nearly two square miles of the land nearby. The farmstead site is eligible for listing on the National Register of Historic Places.

The Joliet Arsenal Ammunition Plant was active under the auspices of the U.S. Army on this land for 60 years. During World War II, the arsenal was the nation’s leading producer of munitions. In 1993, a citizen’s advisory committee was tasked with finding a way to re-purpose the land. There were many ideas on what could be done with these 23,000 acres.

In February of 1996, the Illinois Land & Conservation Act was signed by U.S. Congress.

This is how the land was divided:

455 acres were allotted for a landfill to be used by Will County. If you look to the southeast of where you now stand you will often see trucks atop the highest point in Will County.

982 acres were set aside for what was to become the Abraham Lincoln National Cemetery.

3000 acres were divided into two industrial parks at the north and south ends of Midewin.

19,161 acres were given to the U.S. Forest Service to become Midewin National Tallgrass Prairie.

Planting a prairie didn’t start immediately. A plan had to be made. A temporary headquarters was established in an old farmhouse and staff were hired. Drain tiles, roads, and old buildings were removed. Removal of invasive plant species continues.

Twenty thousand people worked at the Joliet Army Ammunition Plant at its peak workforce in the 1940’s. The arsenal provided jobs for people as far away as Joliet & Chicago.

Built outside Wilmington were seven army type barracks with 28 one room & 28 two room apartments. A 200 unit trailer park and 500 homes were built by Federal public Housing Authority in Wilmington. Employees’ lives revolved around the arsenal. Even after work they socialized at the arsenal.

The Arsenal included amenities like a swimming pool, hunting and fishing areas, 4 bowling alleys, theater, hospital, 275 seat cafeteria, ball diamonds, tennis courts, pistol range, and 2 newspapers. There were intramural sports teams formed by arsenal groups in softball, basketball, archery, and bowling.

During the Arsenal era, recreation was more about athletic sports both indoor and outdoor. Today, recreation on this same land has become more about connecting to the land. The seasonal pastime of hunting deer and turkey are very popular. Hunters enjoy communing with the land. Sometimes they are successful and leave with food for their table but not every day hunting ends in success. Hunting also helps keep white-tailed deer and turkey populations at sustainable numbers for the amount of open land at Midewin. Hunting by bow is the predominant style of hunting permitted at Midewin. Although, there are several weekends for shotgun and muzzle loader hunting allowed by lottery through the state of Illinois Department of Natural Resources. Hunters must stay 150 yards away from trails and follow all state and federal regulations. During hunting season staying on trails is recommended and wearing orange is never a bad idea.

Midewin currently has 34 miles of trails. Some of these trails are multi-use for hiking, bicycling, and horseback riding, while others are solely for hikers. No motorized vehicles are allowed for recreation here, although work vehicles are used to traverse this large space. Birding and photography are popular at Midewin, too. If enough snow settles on Midewin, hardy folks have been known to cross country ski or snowshoe.

Programs and events abound at Midewin. The history of the people who lived and worked on this land is important. Learn about the American Indians, the European settlers, and the Arsenal workers through programs. If natural science is more your speed there are many options to satisfy this need, too. Midewin offers programming for kids, families, and adults. We schedule outdoor programs for the warmer months and offer a lecture series inside in the winter months. Finally, the newest and biggest change is people visiting the bison pasture to try and get a glimpse of the recently introduced herd.

Midewin is public land that is managed by the United States Forest Service.This land is held in trust for the American people by the federal government. The public are considered shareholders of the prairies, wetlands, savanna, and creeks that exist at Midewin.Come enjoy this land that belongs to you, the public.Connect to the land through recreation and the programs on history and nature.

In 1939, the United States had little capacity for large scale manufacture of military munitions or military weapons at the start of WWII. The United States decided it would solve this problem by building specialized munitions manufacturing plants that were government-owned and contractor-operated or GOCO for short. Seventy-seven of these GOCO plants were eventually built across the United States.

On September 17th, 1940 an announcement was made that an ammunition plant would be built in Will County, Illinois. Three days later, it was learned that not one, but two plants were being planned for Will County. These plants would be two of the first five large scale munitions manufacturing plants to be built in the United States.

The government had specific criteria they followed in selecting new plant locations. Sites needed to be 200 miles from the United States borders to protect plants from possible enemy air attacks. There must be reliable transportation of highway, railroad, or waterway nearby to easily transport munitions. The Will County site boasted highway Route 66 (now Il Route 53), the Santa Fe and Chicago & Alton Railroads on the west side and the Wabash Railroad on the east side. A large labor force was also necessary to man the plants. This site was in commuting distance to the cities of Joliet and Chicago. Yet, the location must also be far from highly populated areas in case of explosion. Additionally, the site must be level, have access to electric, oil pipelines and an abundant water supply. Lastly, the land must be relatively cheap. Many farms in this area of Will County were financially “under water”, so the incentive was there for farmers to sell their land. Furthermore, many farms were already owned by financial institutions, many of which were more than happy to sell. The land meeting all these criteria was rich farmland located between the towns of Elwood and Wilmington along Route 66 which would be renamed Route 66A or “Alternate”.

Land purchase negotiations began on September 18th of 1940. 36,645 acres of land were purchased from 225 landowners at a cost of $8,176,815. Farmers were paid a fair market value for their land plus improvements. They were also given either 30, 60, or 90 days to vacate the property. Construction stared in mid-November of 1940 on both plants. This meant construction commenced before farmers received the checks for the land purchases in late November. The push to get plants running and producing munitions for the war was on. In less than a year, both plants were producing munitions.

Kankakee Ordinance Works was built south of Elwood on the west side of Route 66A. Kankakee Ordinance Works produced primarily TNT as well as other chemical compounds used in explosives. Most of these products would be shipped via intra-plant railroad to the plant being built on the east side of Route 66A. Located southeast of Elwood and northeast of Wilmington, was the Elwood Ordinance Plant. The mission of this plant was to load and assemble shells, bombs, fuses, detonators, boosters, and primers with explosives. 17,000 construction workers were hired to build these two plants. The construction cost of the two plants totaled $81 million. This included a total of 1,462 buildings for both plants. 882 of these were located on the east side and 580 buildings on the west side. Within the arsenal 166 miles of railroad and 220 miles of road were built. The facility was enclosed by miles of 8-foot chain link fencing topped with 2 feet of triple strands of barbed wire string. The hourly wage for construction workers started at $0.90 for general laborers, $1.50 for plumbers and up to $2 for general foremen. Much more than just the cost of the buildings was figured into the final price tag.

Elwood Ordnance Plant began operation of a medium and major caliber line on July 12th of 1941. Kankakee Ordinance Works began production in Acid Area No. 1 on September 8th of 1941. Both plants were also well known for their ammunition production training schools during WWII. The nickname of the Elwood Ordinance Plant was the “WestPoint” of ammunition. This was due to its extensive training program for United States plants and personnel as well as those from other allied countries including China.

The peak number of employees for both plants combined reached 20,000 in July of 1942. These folks worked round the clock in three shifts. Hourly wages at the plants were $1.02 for the average worker, $0.86 for office employees, and $1.35 for railroad laborers. Three fourths of the arsenal positions were reserved for farmers displaced by the purchase of their land. As the United States became more embroiled in WWII, more men left the workforce on the Homefront to join the military. In 1941, extreme labor shortages at the two GOCO plants here were filled by women and contracted laborers from Jamaica and Barbados. About 25% of the workforce at the Joliet plants during WWII were women.

The arsenal plants did more than make chemicals and munitions during WWII. The 732nd Military Police Battalion was stationed on surplus land around the Kankakee Ordinance Works. This MP battalion was an all African American unit and their camp was located adjacent to the Des Plaines River. It was known as Camp Des Plaines and was originally built in 1941 for the contracted workers from Jamaica and Barbados. This Battalion was hailed in the press for helping save Beardstown, Illinois during a massive spring flood along the Illinois River in 1943. An agricultural leasing program also came into being during WWII. This program allowed both plants to put surplus land around the plants into crops and grazing at a time when food shortages were critical. A land leasing program for both crops and grazing still exists on former arsenal lands today.

On August 14, 1945, V-J Day or Victory over Japan Day, all production of munitions ceased and actions for plant lay-away were undertaken. Both plants were closed by September of 1945 and placed on standby status controlled by the government. Within a month, facilities were combined into one large organization and the whole complex renamed the Joliet Arsenal. In post-war years fertilizer was manufactured at the Joliet Arsenal for use in the European Recovery Program, also known as the Marshall Plan. Ammunition reclamation and experimental bomb loading also continued.

The Joliet Arsenal remined in standby mode between December 1946 and May 1950. This would allow the munitions and TNT units to reactivate in the event of military conflict. With the advent of Korean War, reactivation started in June 1950. Production at the facilities continued until July 1953. The end of hostilities in Korea put the Joliet Arsenal once more back into standby status. In August 1964, the facility changed its name to the Joliet Army Ammunition Plant.

The tensions in Southeast Asia turned to war in Vietnam causing both units to be reactivated in 1965. By 1969, the plant reached peak production rates. The end of the war in Vietnam came in April of 1975. The Joliet Army Ammunition Plant was declared inactive in 1976 although due to longer term contracts, some production continued at the plant into the mid-1990s. TNT production ceased for good in 1977.

As contracts were coming to an end, the arsenal property was declared surplus in 1993, by the United States government. Extensive planning sessions with the public and government prepared for the transfer of this surplus property to other hands. In 1995, a task force was formed under Illinois Congressman, George Sangmeister. A bill was introduced to the United States Congress to create the Midewin National Tallgrass Prairie, Abraham Lincoln National Cemetery, the Center Point Industrial Area and Island City Industrial Park, and the Will county Landfill. On February 10th, 1996, the bill was passed into law as the Illinois Land Conservation Act (PL 104-106), and except for parcels of land that still required clean-up, the land was transferred, ending the Army’s 56-year tenure on the land. This Opened a new chapter, one of restoration, to return to return to prairie as the Midewin National Tallgrass Prairie.

Arsenal Workers On the Home Front were a part of what the President Franklin D. Roosevelt referred to when he spoke of everyone being an important part of the war effort during a fireside chat with the nation. At one of these chats on April 28, 1942 President Roosevelt said the following: “But there is one front and one battle where everyone in the United States—every man, woman, and child—is in action, and will be privileged to remain in action throughout this war. That front is right here at home, in our daily lives, and in our daily tasks. Here at home everyone will have the privilege of making whatever self-denial is necessary, not only to supply our fighting men, but to keep the economic structure of our country fortified and secure during the war and after the war.”

In preparation for America’s entry into World War II, funding was appropriated to construct Government Owned-Contractor Operated or GOCO munitions plants throughout the US. In late 1940, the federal government purchased 36,612 acres of farmland here. Then they contracted two plants to be built. The Kankakee Ordnance Works for the manufacture of high explosives on the west side of modern Route 53. The Elwood Ordnance Plant for loading, assembling, and packaging of munitions was built on the east side of Route 53. In short order 229 farm families were moved, and over 17,000 construction workers set to work on building the plants. Elwood Ordnance Plant came on-line in July of 1941 and the Kankakee Ordnance Works in September of 1941. After WWII the two plants joined to become The Joliet Arsenal and in the 1960s the name was change to the Joliet Army Ammunition Plant.

President Roosevelt said in his “Fireside Chat” that all of America was truly called to serve and sacrifice. a The Supreme Sacrifice happened at this arsenal site in the pre-dawn hours of June 5, 1942. While the battle of Midway raged in the Pacific, 48 civilian arsenal workers were killed in an instant. It occurred at Load Assemble and Package or LAP Group 2, about 4 miles east of this spot. Just after the night-shift lunch break, antitank mines were being loaded into railroad box cars. There was a smaller explosion followed immediately by a much larger explosion. The blast was felt as far as Waukegan, Illinois, 60 miles away.

Those lost were mourned, the injured recovered, and safety procedures were reviewed and improved. The damaged parts of the plant were rebuilt and within 60 days Group 2 was back in service. This loss was not to be the last that the arsenal would suffer during the years of WWII. Another tragic sacrifice happened on July 11, 1944. Three arsenal firefighters, Edward Markstrom Jr of Joliet, Orville Milton of Wilmington, and Archie W. James of Kankakee were killed. On March 24, 1945, another explosion took place at LAP 3. It claimed the lives of two more employees listed on statue.

In total, 53 civilian lives were taken at the Elwood Ordinance Plant and the Kankakee Ordinance Works during World War II.

There is a Tale of Two Statues to honor the memory of the lost arsenal workers. In the late 1990s the Joliet Arsenal Memorial Committee began to raise funds to create a statue to commemorate their fallen co-workers and loved ones. It was dedicated on June 9th of 2001. It was located on land adjacent to the edge of the Abraham Lincoln National Cemetery. In 2005, the statue was stolen. Again funds were raised by the Arsenal Workers Association to replaced it. The original statue was recover in 2008 and now stands in a park in the town of Elwood. The Statue located here is the second statue. It was donated by the Arsenal Workers Association to the Midewin Heritage Association, and they in turn donated it to Midewin National Tallgrass Prairie, USDA, Forest Service. It was moved from the edge of the National Cemetery in 2022 to this location, on the grounds of what had once been, “the Joliet Arsenal.”

The structures you see to the north of the trail go by several names, bunker, igloo, and magazine. In the United States, buildings for storing ammunition and explosives have been necessary since 1775. In the late 16th century the word magazine referred to a storehouse used to contain arms, ammunition, and explosives needed for military use. By the mid-19th century, the meaning of magazine changed to describe the chamber for holding a supply of cartridges in a firearm. In modern times, magazine has gone back to being a military store for arms, ammunition, and explosives.

Magazines from 1775 to 1926 were above ground buildings made from stone or brick. After military conflicts, magazines tended to become overloaded with leftover ordnance. In 1926, an electrical storm occurred at the Lake Denmark Ammunition Depot in New Jersey. There was a lightning strike on magazine number 8. Within five minutes, this magazine exploded and threw embers and debris as far as one mile away. This explosion was the start of a chain reaction causing another magazine and a shell house to explode. Nineteen people were killed and fifty injured. The damage to munitions and structures exceeded $40,000,000. The military searched for the facts in this disaster while the public expressed their horror at this disastrous explosion.

The Lake Denmark Disaster spurred Congress to approve the First Deficiency Act in 1928. This Act proposed a joint army-navy board to survey the safety conditions of ammunition storage. Before the Disaster of Lake Denmark, all magazines were above ground structures. This disaster pushed underground magazines to the forefront of safety concerns. The preferred design for magazines became the earth-bermed, concrete igloo magazines. Yes, there are igloos in Illinois today and there have been since 1941. These underground magazines picked up the name “igloo” from their resemblance to the dome shaped Eskimo structures.

At the Joliet Army Ammunition Plant, there were 395 igloos in 6 fields. Igloos, on the west side of Route 53, stored trinitrotoluene more commonly known as TNT. Other products produced and stored on the west side included DNT, its accessories, sulfuric acid, nitric acid, and sellite as well as lead azide used for primers, and tetryl used for boosters, fuzes, and detonators. Igloos on the east side of Route 53 housed bombs, shells, and mines. Components of these munitions, detonators boosters, and fuzes, were also stored in these igloos while waiting to be assembled in one of the four Load, Assemble, and Package plants know as LAPs for short. Munitions were then stored in igloos until they were shipped out to the military.

Igloos at Midewin are 26 feet wide with lengths of 40, 60, or 80 feet. The floors are poured cement with a 2 foot deep foundation. The barrel arched concrete walls and ceiling are reinforced with steel rods. Blueprints show the cement walls as one foot thick. Three feet of dirt cover the roof with up to fifteen feet of dirt on the back and sides of the structure. The igloo was designed to propel any explosion upward and avoid the chain reaction disaster that occurred at Lake Denmark Ammunition Depot. This design intended for the roof to be the weakest point in the structure. In 1948, there was an explosion in an igloo at an ammunition depot in Savanna, Illinois. The urban myth states that the 1,200 - 1,500 lb. door was blown off its hinges and into the Mississippi River, never to be seen again. The truth, as told by a Savanna Army Depot worker, is that pieces of the door were found but not in the Mississippi River, since the igloos were located some distance from the river. It appears that the door may then be the weakest point of the igloo.

The arrangement and the distance between igloos was also configured to help minimize an explosive chain reaction like that at Lake Denmark. These igloos are staggered, so no building is directly in front of or behind another. The igloos are 425 feet apart from side to side, somewhat longer than a football field. The rows of igloos are 800 feet apart. The number of bunkers in a group varies. The doors of all the igloos are on the same side to allow easy access by rail. Raw product and finished munitions were moved within the Joliet Army Arsenal Plant by rail. Signs that were once on igloos designated the number of pounds of explosives that could be housed in each building and the maximum number of workers that could be in the igloo at any one time.

Any condition that exposes munitions to water can lead to misfires and incomplete detonation and could have a profound effect on their safe use. Igloos sport a cement chimney for ventilation of stored munitions as well as floor drains running along walls to drain any condensation. The bermed earth of the igloo has a second benefit. It insulates the igloo creating a constant temperature range between 40 – 60 degrees Fahrenheit. This is important for TNT storage. A constant cool temperature will mitigate the increased risk of accidental detonation due to extreme high temperatures. Other protective measures taken for igloos included lightning rods to ground the structure, hooking railroad cars to a grounding cable during loading and unloading, and screening of vents to prevent wildlife from entering the igloos and chewing open packing materials. In addition, grass growing around the igloos was kept short to prevent grass fires from getting too close to the explosive contents.

What you see at Midewin are Army Standard Igloo Magazines or Type 49s. There were a few variations in igloo design but most modifications to the igloo design were made to alleviate the material shortages and slash construction costs occurring during WWII. Over the course of WWII, 10,000 ammunition and explosive storage structures were built across the United States. Igloo magazines provided a safe space for the storage of munitions. This was extremely important in focusing the attention of the military and the public on the military conflict and not disastrous explosions at home.