Volume 204: The Soo Locks, Part 2

This article is the second of a series on the Soo 

Locks, which are operated and maintained by the 

Detroit District of the U.S. Army Corps of 

Engineers (USACE). In part 1, the history of the 

locks through the early 1940s was presented. As 

construction is being planned for a new lock, part 

2 is a look into the modern facility complete with 

information on the project. 

While plans for a new lock (later known as the 

MacArthur Lock) had been initiated by the

USACE back in 1940, that process was expedited 

by a number of events which occurred between 

that time and December of 1941. Of these events, 

the most relevant to the need for increased 

attention at the locks included the attack on Pearl 

Harbor, the bridge span collapse in the North 

Channel of the Soo Locks facility, and the record 

breaking 110.7 million tons of freight moved 

through the Sault in the 1941 shipping season. 

After a great deal of pressure from the industry fell 

on A.T. Wood, then President of the Lake Carriers 

Association (LCA), he reached out to the Army 

regarding the matter. 

Initially, Wood pointed out the need for additional 

aircraft defenses at the Sault. After some time

Wood was directed to reach out to the Secretary of 

War, Henry Stimson, in a letter dated January 19th, 

1942, where he requested that Stimson “review 

measures which have been taken to protect the 

canal against possible sabotage or attack.” There 

was some back and forth between Wood and the 

Army, which led to Wood reaching out to a newly 

created group entitled Office of Defense 

Transportation (ODT). This was a group which 

replaced the transportation division of the National 

Defense Advisory Commission (the group 

Roosevelt put in place to oversee his defense 

program). Ultimately, the response to this outreach 

and the aforementioned events was a great deal of

increased security at the locks. In February 1942,

the General Marshall ordered that the military 

police battalion on guard at the Soo be reinforced 

by a detachment of the 100th Coast Artillery and a 

barrage balloon battery.

Of note, on March 5th, 1942, Joseph Eastman, the 

Chief of the ODT, received a War Department 

response indicating that “the Chief of Staff 

personally expressed a keen interest in the 

protection of this key to the lake transportation 

system” and that “measures would be taken soon 

to increase the defenses from both ground and air 

and to make sabotage by means of blocking the 

channel much more difficult” while the War 

Department “naturally hesitates to publish exact 

measures taken.”

In fact, a great deal of thought and attention was 

given by the Army as to what required action was

needed to safeguard the Soo Locks. There were 

both active and passive protection measures in 

place to protect the Soo Locks complex. Further, 

Sault Ste. Marie was designated as a ‘Military 

Area’ during the war. Some of the main threats 

which, by survey of the Army General staff, were 

probable, included sabotage, direct attack by 

submarine or aircraft from the Hudson Bay region, 

and land based attack from northern European 

bases. 

As mentioned above, barrage balloons (along with 

weapons and air warning equipment) were 

deployed as active measures to protect against 

attack. Special construction, required to complete 

these defense installations, was completed. This

construction included the fabrication of balloon 

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beds, platforms, and towers. Further, there were 5 

warning stations constructed (1 in the United 

States and 4 in Canada) to give advance notice of 

any potential threat. Close contact was kept with 

Canadian agencies to keep an eye on any and all 

construction in the area of defense. In addition, 

passive measures were taken which would protect 

the locks in the case of an emergency. These 

included the furnishing of critical spare equipment 

(including spare steel gates, usable for the Davis 

and Sabin, stored at the river bottom), the 

installation of torpedo nets in lock approaches, and

the design and installation of a standby electric 

powerplant.

Additionally, all of this attention helped in

securing lock funding by February of 1942. Soon 

following this, Congress authorized the new lock 

project on March 7th, 1942, and the bids for 

removing the Weitzel Lock, constructing the 

necessary cofferdams in the upper and lower 

approaches, and excavating the site for a new lock 

were received in the same month, with work 

started in the field in April. Soon after, a contract 

was entered into to construct the lock proper with 

the same contractor responsible for these initial 

tasks, under the stipulation that the lock be 

completed no later than the 4th of July, 1943. 

EARLY DEMOLITION WORK ON THE OLD WEITZEL LOCK 

It had already been decided that the construction 

would be executed as an emergency measure with 

work carried on through the winter time. Once 

construction began, the project was placed on a 7-

day around the clock schedule with over one 

thousand workers employed on the project. One of 

the engineering considerations associated with the 

MacArthur Lock was the plywood structures built 

over each section of the lock with electric blowers 

utilized to heat these buildings - allowing workers 

to continue to pour cement despite the extreme 

cold in the winter. Another noteworthy point is that 

the lock construction involved over 200,000 cubic 

yards of concrete and furnishing and fabricating 

about 3,200 tons of steel for gate, reinforcing steel, 

and operating machinery. On July 2nd, 1943, a full 

two days ahead of schedule, the construction was 

completed and the lock filled with water. Unlike 

previous locks, the lock was named the MacArthur 

prior to the completion of construction – by an act 

of Congress of June 15th, 1943. The total cost of 

the lock and its approaches was nearly 14 million. 

This estimate did not include additional new work 

which was completed simultaneously during the 

project, bringing the actual total of construction 

costs to more than 18 million.

MACARTHUR LOCK UNDER CONSTRUCTION

The near completion of the MacArthur Lock along 

with the installation of torpedo nets, sandbagging, 

hardening of critical components, manufacturing 

and offsite storage of spare parts provided enough 

redundancy/resilience to allow a drawdown of 

troops to begin in May of 1943. By December of 
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1943, all additional military units were removed 

and a single battalion of military police were 

guarding the locks, the same size as the force that 

had been in place prior to the 1942 buildup. During 

wartime, it’s noted that there was not a single 

incident of sabotage which occurred at the Soo 

Locks, or in the Great Lakes as a whole.

When considering the span of time devoted to the 

history of the locks, it was not long after the 

completion of the MacArthur Lock that another 

deep draft lock was anticipated by Congress -

which had authorized a new lock construction in 

1946. While the original dimensions of this new 

lock (later known as the (Second) Poe Lock) were 

800 feet long in 1958, this was adjusted several 

times (even after construction work had already 

begun!) until the size of the proposed lock 

increased to 1,200 feet long by 110 feet wide in

August of 1962. Construction had begun in 1961 

with placement of cofferdams, excavation, and 

removal of the (First) Poe lock. The first 

commercial ship to test the lock, the steamer Philip 

R. Clarke carrying 18,000 tons of taconite, locked 

down on October 30th, 1968. Thus, the 

construction of the new lock, including excavation 

and removal of the old, took a total of 7 years. 

While the total project cost was approximately 40 

million the cost of the (Second) Poe lock alone was 

over 21 million dollars. 

While there were certainly trials associated with 

the construction of the (Second) Poe lock, one 

major test encountered was that it was built 

between two existing locks (speculated to be the 

first of its kind). Several challenges arose from 

this, including how to continue traffic on either 

side of the construction site and how to ensure 

stability of the walls between the excavated area 

and the adjacent locks. Some of the major 

engineering considerations for the (Second) Poe 

lock include two groups of lateral culverts under 

the lock floor, configured in a way to minimize any 

turbulence associated with filling and emptying 

the lock, and four safety booms (one boom on each 

side of the operating gates) which were designed 

to prevent out of control vessels from striking a 

gate. While the lock had been tested in October of 

1968, a formal dedication did not occur until June 

26th, 1969 – when it was officially named the 

(Second) Poe Lock. 

SECOND POE LOCK UNDER CONSTRUCTION

PHOTO COURTESY OF SOCIETY OF AMERICAN MILITARY ENGINEERS –

OBTAINED FROM A REPRINT OF AN ARTICLE IN THE JANUARY/FEBRUARY 

1966 ISSUE OF MILITARY ENGINEER MAGAZINE.

By 1972, the Davis and Sabin were both over 50 

years old and nearing the end of their useful 

economic lives. Given that they could only handle 

21 feet in draft, only older boats used them with 

any regularity. With this is mind, it was less than 

three years later – in February 1972, when the 

Detroit District Engineer was given approval by 

the Chief of Engineers to conduct a study 

considering whether to replace one or more of the 

locks at the Sault. Despite early progress, it was 

several years later when the construction was 

actually authorized by the Water Resources 

Development Act (WRDA) of 1986. Now it was 

just a matter of funding.

While a report calculating a Benefit to Cost Ratio 

(BCR) of a new lock became publically available 

in 2005, it has since been proven to have inaccurate 

assumptions (including that rail capacity was 

sufficient to handle movement of commodities in 
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Page 4

the result of a lock closure). Still, progress was 

made in the WRDA of 2007, allowing construction 

of a new lock at full federal expense. In 2014, a

report was released containing information 

gathered from a group of stakeholders whom were 

both reliant on the locks and considered experts on 

the subject. This report determined that a more indepth study, introducing a reevaluation of the 

economic analysis, was warranted. This study

(titled the Economic Validation Study) was 

completed in 2018, establishing a new BCR of 

2.42 in order to seek an updated authorization for 

construction. This authorization occurred in the 

WRDA of 2018, allowing construction at a cost of 

approximately 1 billion dollars.

According to the Economic Validation Study 

completed in 2018, the regional impact of the new 

Soo Lock construction is 1,125 jobs each year for 

8 years generating 559 million dollars in labor 

income, 1.82 billion dollars in business revenue, 

and 833 million dollars in gross regional product. 

The project will have identical dimensions to the 

existing (Second) Poe Lock, in order to ensure the 

continued ability of the facility to handle the 

largest freighters which transit the locks. The 

project will use more than 735,000 tons of 

domestically-quarried limestone, 35,000 tons of 

American-made cement, and 20,000 tons of 

American-made steel.

Several recent strides have been made in securing 

funding and furthering progress on construction of 

the new lock following the release of this study. 

The Army’s Civil Works program gave the Detroit 

District of the USACE 32 million dollars in 

funding in the Fiscal Year 2019 Workplan for 

phase 1 of construction of the upstream channel 

deepening (a project is aimed to allow the North 

Channel to accommodate freighters with the same 

draft in which the South Channel allows). Further,

in December of 2018 the State of Michigan 

provided 52 million dollars to help expedite the 

overall construction process for the new lock. 

Construction on the upstream channel deepening 

project is scheduled to begin this upcoming spring 

(2020).

ARTISTS RENDITION OF THE FUTURE SOO LOCKS COMPLEX

The U.S. Army Corps of Engineers, Detroit District 

would like to thank Lake Superior State University 

and Bayliss Public Library in Sault Ste. Marie, MI for 

access to their immense wealth of knowledge on the 

project.

Sources:

• Arbic, Bernie. City of the Rapids: Sault Ste. Marie's

Heritage. The Priscilla Press, 2003.

• Arbic, Bernie, et al. Upbound Downbound: The Story of 

the Soo Locks. The Priscilla Press, 2005.

• Aune, C A. “The Soo Locks - St. Marys River, Michigan.” 

Military Engineer, May 1965.

• GLD in WWII, U.S. Army Corps of Engineers, 1946, 

pp.43-45, 125–136. Obtained at Bayliss Public Library.

• Joachim, George J. Iron Fleet: The Great Lakes in World 

War II. Wayne State University Press, 1994.

• Larson, John W. Essayons: A History of the Detroit 

District U.S. Army Corps of Engineers, 1841 and Forward. 

2nd ed., U.S. Government Printing Office, 1995.

• Pletcher, Ben. “Lockdown: The Story of the Soo Locks and 

WWII.” Military History of the Upper Great Lakes, 

Michigan Technological University, 16 Oct. 2016, 

ss.sites.mtu.edu/mhugl/2016/10/16/3312/.

• Stevens, Deidre. “When World War II Came to the Sault.” 

Michigan History, www.hsmichigan.org/wpcontent/uploads/2012/02/MHM_MarAp_Sault.pdf.

• U.S. Army Corps of Engineers. The 40th Anniversary of 

the Poe Lock, 1969 to 2009. The 40th Anniversary of the 

Poe Lock, 1969 to 2009, U.S. Army Corps of Engineers, 

2009.