A tour of the Carrie Blast Furnace on the Monongahela River in Pittsburgh brings our region’s role in American industrial history to life.
If you’ve ever visited the Henry Clay Furnace at Coopers Rock State Forest, you’ve seen a cold blast furnace for smelting iron. It needed just four inputs. Workers layered charcoal made from the surrounding trees with iron ore and limestone mined nearby. A steam-powered blower engine injected the fourth input, air, so the charcoal would burn hot—and the result was four tons of pig iron a day. Neighboring Jackson’s Ironworks turned that iron into cut nails and cast-iron stoves and boated them down the Cheat and Monongahela rivers to markets. The two businesses anchored a community of several thousand residents in the 1830s and ’40s.
Four tons a day sounds like a lot, but U.S. ambitions after the Civil War—railroads, bridges, skyscrapers—demanded steel, and that called for vastly more pig iron. Using coal instead of charcoal and a more efficient hot blast process let producers meet the demand.
Just like the Henry Clay cold blast furnace, the larger hot blast furnaces needed to be near inputs and transportation. Pittsburgh, sitting between high-quality Appalachian coal and Great Lakes iron ore and on ready river transport—and home to industrialist Andrew Carnegie—became the birthplace of American Steel: Steel City.
At the steel industry’s peak in the 1970s, some 125 hot blast furnaces operated across the U.S. Almost a quarter of those, around 30, sat on the Monongahela River near Pittsburgh, a source of the city’s famously poor air quality.
Today, only about a dozen blast furnaces operate in the U.S., and Pittsburgh’s air is as clean as anywhere. Modern smelting methods are very different but, at Pittsburgh’s Carrie Blast Furnace, you can walk through a giant 20th century iron smelter and get a real feel for the dominant role the Mon River Valley played in American industrial history.
Pig Iron at the Industrial Scale
“In Pittsburgh, there’s a tradition of naming furnaces for women,” says Barney Terrell, curator of collections and one of dozens of Industrial Tour guides for site manager Rivers of Steel Heritage Corporation. “We have Isabella, Eliza, Dorothy, and on down the line.” Carrie, which produced its first iron in 1884, was named for a cousin of the founders, Caroline Clark. The furnace was built to supply iron to Carnegie Steel’s Homestead Steel Works directly across the Monongahela River, and, in 1898, Carnegie bought it. He turned around and sold it all to U.S. Steel in 1901, and Carrie was with U.S. Steel until it closed in 1984, its 100th year.
The site is bewildering on first impression: towering vessels, massive pipes running at angles, scaffolding jutting into the sky. The tour guides make it all make sense over the course of the tour, painting a vivid picture of 20th century iron-making and connecting it all to life in Pittsburgh today through two hours of lively, relatable storytelling.
Of Carrie’s multiple blast furnaces, only Nos. 6 and 7 remain today. They stand 85 feet tall at the center of the complex. Surrounding and cross-crossing the site are rails for taking raw materials in and finished iron out. Carrie used the same four inputs as Henry Clay:
- Not charcoal here, but coke—coal that’s been purified so it burns even hotter than coal and introduces less sulfur into the iron, making for stronger steel.
- Iron ore. “The vast majority of the iron here was what’s called Mesabi ore, from northern Minnesota,” Terrell says. “It made quality iron and good steel.” When the Great Lakes freighter SS Edmund Fitzgerald of ballad fame sank in 1975, he notes, it was carrying pelletized Mesabi ore.
- Limestone would bind with impurities in the iron and coke to form waste slag. “For every ton of iron these furnaces made, they produced about 200 pounds of slag. You cannot swing a dead cat in this region without hitting slag.”
- Finally, the supply of air took up a lot of the real estate. “These are hot blast furnaces, so you’re pushing hot air in there instead of cold,” Terrell says, pointing at the huge brick blowing engine house. “You have the air being pushed from that building into the stoves, those six silos. They will heat the air up and then force it into the furnaces.”
The fuel, ore, and limestone were hauled in “skip cars” 24/7 from a massive store house to the top of each furnace and dumped in to form layers. Molten iron came out at the bottom. At this scale, the iron wasn’t flowed into the rows of ingot molds that make it look like piglets at a trough—hence the name “pig iron.” Here, it went into insulated rail cars that carried it across the river to the steel works.
The scale of the operation is hard to grasp. While Henry Clay made four tons a day, Carrie Nos. 6 and 7 each produced, at their peak, 1,250 tons a day—and they were only part of the operation. In the 1950s, Terrell says, around 15,000 employees worked at the Carrie Furnace and Homestead Steel Works in three shifts.
Heavy Industry in Pittsburgh Culture
One stop on the tour is the store house where workers loaded the skip cars with more than a ton of inputs every minute or two. “It would’ve been noisy—you can’t hear anything,” Terrell says. “And dust would have been the biggest thing. Can you imagine? Limestone gives off a lot of dust. As does coke.” Workers routinely had respiratory problems, hearing loss, and repetitive strain injuries—and that affects the economy even today. “What’s the tallest building in downtown Pittsburgh? It’s the U.S. Steel Tower. Across the top of that building now is ‘UPMC’—University of Pittsburgh Medical Center. That’s not just a metaphor. The medical economy that runs Pittsburgh now was built on the bodies of people working in places like this. They had a huge testing bed, especially for cancer treatments and orthopedics. This is one of the best cities in the world for orthopedics.”
Jobs at the iron mills drew Czech, Ukrainian, and Polish immigrants and others, a source of the city’s diversity today. “Carrie is also unique among Mon Valley mills,” Terrell says, “because we were majority Black after 1950.”
While the air quality in the region was bad, it sometimes got a lot worse. “Look at the top, those four vent stacks there,” Terrell says. “There were sirens that would go off when they vented. One guy told me he grew up near here in the ’50s. When they heard those sirens, he said, ‘My mother would run out and grab the laundry. If I was outside, she didn’t pick my brother and I up because, she told me, “You can wash yourselves, but I’m not doing the laundry again.” ’ ”
The region was clearing up other sources of air pollution by mid-century, and that effort got a boost when the market for American-made steel started to decline in the 1960s. Residents left for jobs elsewhere—a diaspora that means Pittsburgh sports fans easily encounter fellow fans when they travel. “You can find a Steelers bar anywhere,” Terrell laughs. “I found one in Rome. It had a Mean Joe Greene jersey and everything.”
Visiting the Carrie Blast Furnace
Schedule your Carrie visit well in advance—tours are sometimes booked up for weeks ahead. The Industrial Tour circles the facility, then makes a smaller circuit right up between and inside the structures, so dress for the weather and wear sensible shoes. In the hotter months, morning tours are the way to go.
Tours aren’t scripted, so you get a different perspective every time you visit. Rivers of Steel also offers tours with other themes as well as metal arts and graffiti arts workshops, photo safaris, pop-up and permanent public art installations, and the spectacular October Festival of Combustion.
801 Carrie Furnace Boulevard, Pittsburgh, riversofsteel.com
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