Building the MacArthur Lock

A Wartime Feat of Engineering

During World War II, as larger freighters carried vital ore for the war effort, it became clear that the aging Weitzel Lock in Sault Ste. Marie was no longer up to the task. While the St. Mary’s River had been dredged to 24 feet in the 1930s, the Poe and Sabin Locks could only handle vessels with a maximum draft of 20 feet. To keep crucial supplies moving, Congress approved the construction of a new, longer, and deeper lock on March 7, 1942. The new lock would be named The MacArthur Lock after General Douglas MacArthur. The project had to move fast—this was wartime, and delays weren’t an option.

Work began on September 1, 1942, with crews from the Great Lakes Dredge and Dock Company working around the clock. Despite frigid winter temperatures that required heaters to set the concrete, construction was completed in just 16 months. An incredible feat compared to the 6-8 years it had taken to build previous locks. On July 11, 1943, the MacArthur Lock was officially dedicated, with the SS Carl D. Bradley becoming the first vessel to pass through. The construction team even received the Army–Navy E Award for their record-breaking effort.

MacArthur Lock still in Operation

The MacArthur Lock remains a vital part of the Soo Locks system. At 800 feet long, 80 feet wide, and nearly 30 feet deep, it was designed to accommodate both Great Lakes freighters and ocean-going “salties.” While it’s not the largest lock in the system, it played a crucial role. The lock kept the wartime industry moving and remains an engineering marvel to this day.

Next time you visit the Soo Locks, take a moment to appreciate the MacArthur Lock—not just as a piece of infrastructure, but as a symbol of the urgency, ingenuity, and determination that helped power the war effort.

Marisa Fancy along with her husband and four children dreamt of moving “Up North”. They had vacationed for years in northern Michigan and in 1995 they finally made the move.

The family was always out exploring, but with 4 kids there was some limitations on what they could do. Marisa discovered the amazing network of trails in Northern Michigan after Steve died and she would walk for miles. The trails provided her with peace, comfort and solitude at a difficult time in her life. Later, after meeting Guy who would become her second husband, she learned to golf and found another passion she could enjoy in beautiful Northern Michigan.

Marisa has been the family historian, writer, and poet for as long as she can remember. She has always loved to write and has now found a creative outlet for it other than family. You can read her articles in Adventures in Northern Michigan, Northern Michigan History and Golf Up North.