Designed by Consolidated Aircraft of San Diego, California, the B-24 Liberator served in every branch of the armed forces during World War II. Four engines powered the aircraft, and together its two bomb bays could carry up to 8,000 pounds of explosives. Crew size was up to ten, and range was up to 3,000 miles. More than 18,000 were built.

Along with the B-17, the B-24 formed the backbone of the Allies' air war over Europe. In a strategic campaign, the airplanes and their crews attacked factories, railroads, harbors and -- as the war progressed -- cities in Germany, Italy and occupied France. The bombings curbed Germany's manufacturing capabilities and wore down its citizens' morale.

As American involvement in the war seemed more likely, the U.S. government approached Ford Motor Company about making parts and subassemblies for B-24 bombers. For government officials, Ford offered significant advantages. It was the company that perfected the moving assembly line in the 1910s and, as a privately owned firm, it could move faster than publicly traded corporations.

Charles Sorensen, seen here earlier in his career, traveled to Consolidated's San Diego plant with Ford president Edsel Ford. Sorensen was shocked. Planes were assembled outdoors, exposed to a hot sun that distorted parts out of shape. Sorensen could not guarantee that precision parts built by Ford would fit in airplanes built by Consolidated under those conditions.

Sorensen, Edsel Ford and Henry Ford well understood the difficulties in precision mass production. Ford Motor Company had reinvented the concept with the Model T's moving assembly line. The company came back to the government with a counter proposal: it wouldn't just build parts for the B-24, it would build complete airplanes using the automaker's highly refined techniques.

Working with architect Albert Kahn, Ford officials envisioned a massive factory with bombers built on a moving line, just like Ford's automobiles. The main building would be more than a mile long with dual, parallel assembly lines. The chosen site was farmland owned by Henry Ford on the eastern edge of Michigan's Washtenaw County, near a creek called Willow Run.

Plant construction started in March 1941. The main building went up in sections, with workers using plywood partitions to seal off finished portions from those still under construction. Five main contractors hurried the project along, and parts of the plant began production in September 1941. Ultimately, more than seven million square feet of floor space were completed for B-24 production at Willow Run.

Adjacent to the factory complex, Ford constructed a 1,484-acre airport with six runways and three aircraft hangars. The largest of these hangars could house 20 B-24s at once, and included a control tower, a cafe, and a hotel. The Willow Run plant was formally dedicated on October 22, 1941, in a ceremony attended by Major Jimmy Doolittle of the U.S. Army Air Forces.

At its peak, Willow Run employed more than 42,000 people. Simply moving workers to and from the plant was a major logistical challenge. It sat 35 miles west of Detroit, at a site without existing highway or streetcar connections. Buses were among the only practical solutions. Public bus lines offered 35 daily trips from Detroit, while private carriers offered 130.

Highway improvements came in September 1942 when the Willow Run Expressway opened between the plant and Detroit. The tri-level interchange seen here provided direct access to the factory for traffic traveling to and from the expressway. The Willow Run Expressway also connected with the Detroit Industrial Expressway, built at the same time. These highways evolved into present-day Interstate 94.

For those unable to endure a long commute, the federal government constructed housing on nearby farmland purchased from Henry Ford. The Willow Run Lodge dormitories accommodated 3,000 single women and men, while Willow Run Village consisted of 2,500 family housing units. After the war, these residences served students attending the nearby University of Michigan on the G.I. Bill.

Employee training was a constant process at Willow Run. In on-site classrooms, newly hired workers sat through orientation lectures on the aircraft industry in general, the B-24's specific importance to the war, and the dire consequences should the Allies lose the fight. Specialized employees -- riveters, for example -- received training in these classrooms as well.

Charles Sorensen boasted that Ford would produce B-24s at the rate of one each hour. Established aircraft manufacturers, used to a much slower rate, considered the claim preposterous. Sorensen and his team methodically broke the complex bomber plane into 11 major assemblies, and then further divided these into 69 subassemblies. The team developed the B-24's build sequence from these divisions.

Ford struggled to get Willow Run running at full potential. The government's constant design changes to the B-24 were particularly troubling. Ford's production methods depended on a "fixed" design -- each design modification required expensive and time-consuming updates to the assembly line. As the problems continued into 1943, critics took to calling the plant "Will it Run."

Willow Run's problems came under a microscope in April 1942 and again in February 1943, when Senator Harry S. Truman visited the plant. Truman headed a presidential committee charged with eliminating wartime production waste, and Willow Run's struggles worried him. Ford president Edsel Ford and his team explained the difficulties with design changes. Truman was unimpressed -- he didn't want excuses, he wanted finished bombers.

Only 56 airplanes were built in all of 1942. But, as 1943 arrived, problems got solved and Willow Run turned a corner. Numbers climbed steadily throughout the year. Ford built 37 planes in January, 70 in February, 96 in March, and 146 in April. On November 3, 1943, employees celebrated as Willow Run turned out its 1,000th finished B-24 bomber.

Perhaps the most impressive breakthrough at Willow Run was Ford's technique for assembling the B-24's center wing section. Consolidated had built each wing with its own temporary jig to hold the structure in place. Ford created a permanent jig into which wings could be moved in and out by overhead crane. Consolidated's method required 250 man-hours; Ford's needed one.

With so many young men drafted into the armed forces, Willow Run's workforce was unusually diverse for its time: African Americans, whites, older people, younger men unable to serve in the military, and -- most notably -- women. Approximately one-third of the plant's assembly line workers were female. At its peak, Willow Run employed more than 15,000 women -- some 35 percent of its total staff.

Riveting was an essential craft at Willow Run. Each completed B-24 contained more than 300,000 rivets in more than 500 sizes. The skilled women who accomplished this work -- at Willow Run and elsewhere -- inspired the symbolic "Rosie the Riveter" character. Today "Rosie" remains a feminist icon and a powerful reminder of women's contributions to the American economy.

While assembly workers formed the heart of Willow Run's workforce, there were numerous administrative, clerical and support staff members too. The standard workweek for all hourly employees was 54 hours, with time-and-a-half pay for each hour over 40. Women and men were paid the same rate for the same work. Ford recruited workers throughout the Midwest and South.

Feeding the thousands of workers at Willow Run was no small task. Cafeterias provided meals to administrative workers in the plant's offices. Workers on the factory floor could purchase meals from lunch wagons that traveled the facility. There were 24 lunch rooms located throughout the complex. The plant's kitchen prepared nearly 10,000 rolls each day.

To care for the plant's workforce, Willow Run maintained an on-site hospital with eight doctors, 40 nurses, and a dentist. Over the course of the war, the hospital handled more than two million medical cases. While there were many injuries, it is notable that Willow Run did not record a single fatality while the factory was in service.

With the pressures of wartime production schedules -- and the sense that victory itself depended on their efforts -- Willow Run's employees needed occasional relief from their burdens. Baseball games at the on-site recreation field took away some of the strain during off-duty hours. Factory golf and bowling leagues provided additional opportunities for relaxation.

Ford officials looked for every efficiency they could find in B-24 production. Some riveted parts were replaced with cast pieces to simplify and speed their manufacture. Most controversial was Ford's decision to replace soft metal dies -- thought to be gentler on aluminum airplane components -- with hard steel dies. Steel dies proved more precise, longer lasting, and perfectly safe.

At last Willow Run hit its stride in 1944. That April, employees in two nine-hour shifts, working six days a week, produced 453 airplanes in 468 hours -- a production rate equal to one finished B-24 Liberator every 63 minutes. Charles Sorensen's brash "one plane every hour" claim was no longer an empty boast. Willow Run and its workers met their goal.

Sadly, one of the people most responsible for Willow Run's success did not live to see it. Ford Motor Company president Edsel Ford passed away on May 26, 1943. He succumbed to cancer, but the enormous stress of the B-24 project undoubtedly affected his health as well. Mr. Ford's steadfast leadership helped the company to make good on its promise.

In addition to complete airplanes, Willow Run produced "knock-down kits" that were shipped to Douglas Aircraft's plant in Tulsa, Oklahoma, and Consolidated Aircraft's plant in Fort Worth, Texas, for final assembly. Each kit -- consisting of 80 percent of the parts for a finished B-24 -- was shipped via two tractor-trailers. Willow Run workers built 1,893 kits over the course of the war.

Employees at Willow Run celebrated the completion of their 6,000th airplane in September 1944. Ford now planned to build 650 planes each month -- one every 45 minutes. But just when that milestone seemed possible, the government drastically cut its order for B-24s. The war's focus was shifting from Europe to Japan, where more-advanced B-29 bombers were needed. They would be built elsewhere.

President Franklin D. Roosevelt referred to American industry’s war production efforts as the “Arsenal of Democracy.” Willow Run perfectly symbolized Roosevelt’s memorable phrase. The President and First Lady, Eleanor Roosevelt, visited Willow Run on September 18, 1942, where they joined Henry Ford, Edsel Ford and Charles Sorensen on a tour of the complex.

Ford Motor Company built everything from jeeps to generators during World War II, but nothing else was on the scale of Willow Run. The automaker proudly promoted its B-24 efforts in magazine advertisements. Perhaps, when peace returned, customers would remember Ford's achievement when it came time to shop for a new car.

Workers at Willow Run built a staggering 8,685 B-24 bombers -- 6,792 complete planes and 1,893 knock-down kits -- by the time the last one was finished on June 28, 1945. No one had ever manufactured airplanes on such a scale before. Ford proved that even the most complicated military machines could be built using the techniques it pioneered with the Model T.

At war's end, Ford Motor Company chose not to exercise its option to buy the Willow Run plant. Instead, upstart automaker Kaiser-Frazer Corporation moved into the factory. Kaiser-Frazer produced some 739,000 cars at Willow Run between 1947 and 1953, when the company acquired Willys-Overland and moved all operations to the Willys factory in Toledo, Ohio.

After Kaiser left, General Motors leased and then purchased Willow Run. GM first built transmissions at the plant, and later automobiles including Chevrolet's Corvair and Nova models. After nearly 60 years at the site, GM ended its Willow Run operations in 2010. The Yankee Air Museum acquired a portion of the plant, for preservation and exhibit purposes, in 2013.