About once every minute, a new Ford F-150 rolls off the line at the Dearborn Truck Plant in Michigan. It’s a huge building and the largest assembly facility Ford operates anywhere. Even so, it’s a fraction of its former self.

Back in its glory days, it was the Rouge Complex, the largest industrial facility of any kind, anywhere in the world.

It wasn’t originally meant to be any such thing. Henry Ford was building the famous Model T at his nearby Highland Park plant when, in 1915, he bought 2,000 acres of land along the Rouge River. He didn’t have anything specifically in mind for it, and for a while, he thought about turning it into a bird sanctuary. But then the First World War changed everything.

The U.S. government was tapping manufacturers to supply war materials, and Ford was asked to build Eagle Boats, a type of warship. The Rouge property would be ideal since it sat on a waterway, and in 1917, the company built a three-story factory that’s still part of the complex today.

As it turned out, Ford was a better automaker than ship builder. It took much longer to start production than expected, and the first ships leaked. So few were being produced that the government cut back its order of 100 units to 60, and not a single one saw action—in fact, the final ones were delivered more than a year after the war was over.

But now Henry had a plant, and one that could help him realize his dream. Ford always believed in controlling every aspect of manufacturing, instead of being dependent on others. He owned forests, quarries, and mines to produce raw materials, and would later establish two less-than-successful rubber plantations in South America. The Rouge had been widened in preparation for delivery of the Eagle Boats. Now, it could handle ships bringing in iron ore and other commodities that would allow Henry to build his cars from scratch.

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Work began in 1919, and by 1922, the site was home to the world’s largest foundry. The molten iron went directly from the furnaces into molds to make engine parts. By 1926, the complex was making its own steel as well.

The Rouge initially made Model T components for the Highland Park facility, and the first vehicles it produced weren’t cars, but Fordson tractors. The Model A, introduced for 1928, was the Rouge’s first car, as well as the first-ever automobile to be completely produced “from scratch” at a single facility.

The Rouge was at the height of its power in the 1930s. It contained 93 buildings, with a combined floor space of almost 15.8 million square feet, and 193 kilometres of conveyors. The complex included 24 km of paved roads, 160 km of railway track with 16 locomotives, and a city-style bus service with regular stops. More than 100,000 people worked in the facility, which also had a police force, a fire department, and a hospital.

In addition to the foundry and steel mill, the site also included plants that made glass, radiators, transmissions, and tires. There was a paper mill and a plant that made plastic out of soybeans, one of Henry Ford’s pet projects. In the quest to be as self-sufficient as possible, it was all served by an on-site power plant with the capacity to light all of Detroit. That city even bought the Rouge’s excess electricity.

But the Rouge didn’t always run smoothly. To Henry Ford, workers were essentially just cogs in the machine. The pace was fast, breaks were few, and workers were forbidden to talk, smile or whistle. Ford would even send his security forces to check up on workers at home, to be sure they were living up to his standards of keeping a clean house, not smoking, and not taking in boarders.

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So when the United Auto Workers union tried to gain a foothold at the Rouge, Henry dug in. An act passed in 1935 gave workers the right to collective bargaining, and the UAW gained entry into General Motors and Chrysler with the use of sit-down strikes. The union then got a permit to hand out flyers at Ford, and on May 26, 1937, union officials went to an overpass where workers went into the Rouge. They were attacked by Ford security and brutally beaten in an incident that became known as the Battle of the Overpass. Oddly enough, though, when Ford finally accepted the union, Henry gave it the most generous terms of any of the Detroit automakers.

During the Second World War, the Rouge built such military supplies as amphibious vehicles, planes, tank components, and Jeeps. But when Henry Ford died in 1947 and his grandson Henry Ford II took the company reins, the massive complex began to change.

It was partly due to the younger Ford’s desire to decentralize the operations, and partly to outside forces such as tightening environmental legislation. Most of the buildings were old, and retrofitting them for the new standards would be prohibitively expensive. Ford started to get more and more of its components and materials from outside suppliers.

The new-for-1964 Mustang started production at the plant. The Rouge wasn’t the only facility making the new pony car, but the one millionth one rolled off the factory’s floor less than two years later.

The steel plants were spun off as an independent company in 1981, and were sold to Rouge Steel in 1989. The sale cut the original 2,000 acres almost in half and transferred all of the shipping docks and waterfront property to the new owners. By 1992, the Rouge was seriously outdated, and the Mustang was the only vehicle being built there. Ford announced that it would close the plant.

With so many jobs on the line, the UAW sprang into action to work with the company on a plan to update the aging facility. It was a difficult process: in 1999, six workers died when a power plant exploded, followed by a maintenance worker who was killed when overcome by fumes. Ford eventually had to pay more than $30 million in fines and compensation.

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When the Mustang’s production ended in 2004, the complex’s new Dearborn Truck Plant began building the F-150. It closed in 2014 for eight weeks to tool up for the new aluminum-bodied 2015 F-150, including completely gutting and rebuilding the body shop.

The Rouge Complex, now called the Ford Rouge Center, is now just a portion of its former size, but as mentioned, it’s still the company’s largest single facility, covering 600 acres and employing 3,600 people on its assembly lines. As with all newer factories, it was built to be as environmentally efficient as possible, and to that end, there’s a 10-acre “living roof” on top of it. The roof’s four layers are planted with perennial sedum, which filter rainwater to reduce run-off into the river and maintain the factory’s temperature to reduce heating and air conditioning costs.

The Rouge is also one of the few auto plants open to the public, through a joint venture of Ford and The Henry Ford, an independent museum. After watching a movie on the plant’s history, and a multimedia presentation on building the F-150, visitors cross catwalks above the assembly lines to watch workers putting the trucks together below. It’s the latest chapter in the fascinating history of the plant that really put Ford on the map.