Step 2 of my strategic plan: Post my favourite class assignments from the past year, which will start this week with manure and will eventually end with sewage. Enjoy.

We tend to think of nineteenth century cities like Pittsburgh as industrializing under the power of steam. But Joel Tarr argues that an older technology also drove the development of the great cities of the steam age.

In 1775 James Watt patented the steam engine, a machine that would become a symbol of the industrial revolution. Forty years later, Benjamin Latrobe opened a steamboat engine workshop on the banks of the Monongahela River in Pittsburgh. The power source that Latrobe used to build his engines? Two blind horses.

Horses like Latrobe’s were a central cog in the nineteenth century urban economy. They were hooked up to engines through circular sweeps, rotating platforms and treadmills, and harnessed to vehicles on wheels and tracks. City horses hauled steel, powered ferries, pressed bricks. They were the source of valuable manure and even more valuable carcasses. They were the catalysts for the paving of streets and the suburbanization of cities.

But, like the combustion engine, their great success as a technology also contributed to their eventual decline. Thanks to the work of Joel Tarr, a professor of history and policy at Carnegie Mellon University, and his colleague Clay McShane, a professor of history at Northeastern University, we are rediscovering how horses hauled cities like Pittsburgh into the modern age.

Horses at construction site

Horses at Cincinnati subway construction site, probably the 1920s. Image credit: University of Cincinnati Library.

Rediscovering the horse as an urban technology

Joel Tarr thought he was done with horse manure back in 1971. The Jersey City native had joined the faculty at Carnegie Mellon in 1967 with a background in urban political history and an interest in how the modern city had been shaped by transport technologies. During his research, he kept coming across historical complaints that he thought might be interesting to a general audience.

The article he submitted to the magazine American Heritage was a vivid account of the problems faced by a horse-driven city, including the staggering scale of manure logistics:

…as health officials in Rochester, New York, calculated in 1900, the fifteen thousand horses in that city produced enough manure in a year to make a pile 175 feet high covering an acre of ground and breeding sixteen billion flies, each one a potential spreader of germs.

“Urban Pollution— Many Long Years Ago”, American Heritage, 1971

Tarr noted that the eventual solution to these problems was the adoption of a new technology, one that harnessed machines rather than animals. “Apparently the editorial board got into a big fight about it because some of them thought that it was an apology for the automobile,” he recalls.

Controversial from the start, the article prompted several newspaper editorials and is still cited today in debates about pollution. But after creating a stir, Tarr moved on, reasoning that “someone else could worry about the horse manure.” And so he pursued his interests in the environmental and technological history of cities and left the subject of horses alone for more than twenty years.

But while the details of the manure problem lived on in the public imagination, Tarr knew that there was much more to say about the importance of horses in the history of our cities. In 1995, he refused to allow the manure article to be reprinted in an anthology and instead asked if he could write a new article on the topic with his friend McShane, who had recently published a history of cars in cities. From that first article, the project ballooned out into a decade of scholarship and co-authorship of their 2007 book on horses as an urban technology, The Horse in the City: Living Machines in the Nineteenth CenturyThe book is a detailed examination of the centrality of horses to cities, focusing on New York City, Boston, and Tarr’s adoptive home, Pittsburgh.

From steam power to horse power

Tarr and McShane emphasize that the horse was viewed as a “living machine,” valued primarily for its ability to provide power. As machines, horses were an integral part of the economy, even after the advent of the steam engine.

After refining the steam engine, James Watt invented a standard measure of mechanical work – 33,000 foot-pounds of work per minute, or 1 horsepower. This unit allowed customers to estimate how many horses an engine could replace and to gauge whether replacing their horses would be economic. In many cases, it wasn’t. For much of the nineteenth century, horses were the engine of choice for applications that required flexibility or mobility and for businesses that could not afford a large capital outlay.

But the one application in which horses were irreplaceable was ground transport within the city. Goods from the expanded railway and steamboat lines could only be distributed to their final destinations under the power of horses, which meant that horse-drawn transport grew more efficient in parallel with steam technology. Innovations in breeding produced larger and larger horses in the pursuit of (as one agricultural reformer put it) “the best machine for turning food into money.” These industrial-strength horses could pull even larger loads after the development of lighter vehicles made with modern materials.

One resident of Pittsburgh remembered the “pandemonium of noises” produced by horse transport in the 1860s:

Numerous wagons, hauling heavy pigs of iron and iron products, timber wheels with anywhere from six to fourteen horses from which huge and unwieldy vehicles hung castings of many tons’ weight, the clattering omnibus, the rattle of the mail wagons, drays […] and other conveyances common to traffic.

George Thornton Fleming,1904

This was the cacophony of Pittsburgh’s developing steel industry, the sound of a modern city propelled by coal and hooves.

Photo of 1897 traffic

Horse-drawn wagons and carriages, an electric trolley car, and pedestrians congest a cobblestone Philadelphia street in 1897. Image credit: National Archives and Records Administration, 30-N-36713.

Shaping the city

The structure of Pittsburgh’s neighborhoods today still reflects the age of horse-drawn vehicles. Public transport began with road vehicles called omnibuses, but gathered momentum with one of the most influential urban innovations of the nineteenth century, railed “horsecar” lines. These tracks, the precursors of the cable car and electric streetcar systems, provided a smooth ride that omnibuses could never achieve on cobbled pavements that were optimized for horseshoe traction. The benefits of the tracks were not just to the spines of riders, but to the speed the horses could travel, the number of riders they could haul, and the amount of profit their owners could make.

The first lines were laid in 1863 and by 1890 the average Pittsburgh resident took 192 horsecar trips per year. The tracks had grown along the lines of least resistance, following valleys and avoiding the worst of Pittsburgh’s steep hills. As the lines expanded, ridership increased at a rate much faster than population growth, reflecting Pittsburgh’s shift to the suburbs; Residents could now live further away from downtown and make a daily commute to work. Wards within an hour’s smooth ride of downtown were suddenly more desirable than when they were a longer, more expensive and more bone-jarring omnibus ride. The relatively flat Eastside saw the biggest growth – between 1870 and 1890 it grew from 5,350 dwellings to 17,604. Construction boomed in areas within a ten-minute walk of a horsecar line. Tarr and McShane write that “the greater speeds allowed Americans to fulfill the new dream of the middle class, a detached home with a yard on the outskirts of a city.” Meanwhile, downtown was losing residents to the new suburbs and slowly transforming into a true central business district.

Tarr and McShane point out that the horsecar alone did not cause these changes in Pittsburgh and other growing cities. Factors like economic expansion, population growth and a new appreciation for suburban life played an important role, but the horsecar was the technology that allowed these trends to play out, and it set the patterns that were extended in the twentieth century by the streetcar and the gas-fueled automobile.

Problems with the living machine

In 1872, American horses came down with a terrible case of the flu. Several Northeastern cities ground to a dramatic halt. The horse flu epidemic cut off city supplies, grounded fire departments, and isolated suburbs from their vital horsecar lines. When one commentator later warned that another epidemic would reduce New York City to “straits of distress,” he concluded that although “cities have been made by building around the horse there is no necessity for keeping him permanently as their centre.” As the century progressed, more and more objections were made to the city’s dependence on horses.

Like all technologies, horses had their downsides. They were living creatures, susceptible to disease, unreliability, and even personality. They required an enormous infrastructure of foul-smelling stables, with stockpiles of hay that posed a significant fire hazard. But above all, horses were prolific polluters. The average city horse unleashed 25-35 pounds of manure and two to three gallons of urine per day.

Horse manure started out as just one of the many hazards of urban life, but as the century progressed, the exploding city horse population became a source of public angst and newspaper editorials. To make matters worse, by the 1880s the bottom had fallen out of the manure market.

Fresh manure had long been a valued commodity, sold by stable owners and street sweepers to farmers on the urban periphery. But thanks partly to competition from new guano and rock phosphate fertilizers, the price of manure had fallen to less than a quarter of its worth. A New York Times editorial from 1881 conveys the confusion caused by a city decision to declare summer dumping grounds off-limits amidst the glut of manure: “Public health nuisance: No place for stable manure—What is to become of it?” By 1908, one journalist claimed that 20,000 New Yorkers died each year from “maladies that fly in the dust, created mainly by horse manure.” The biggest problem was that the accumulating piles were a favorite breeding ground for flies, a vector for life-threatening diseases like typhoid.

Part of the solution to the manure problem was technological. By 1902 most horsecar lines had transitioned to electric trolleys only a decade after they had been first introduced. But the manure problem itself was not necessarily responsible for the speed of this change. Tarr and McShane argue that in many cases, the new technology was rapidly embraced by horsecar companies because these companies did a tidy side business in land speculation. Horsecar lines had the reliable effect of pushing up property prices wherever they were laid, but by the late 1880s, horsecar lines had mostly expanded as far as they could within a one-hour commute of downdown. With the increased speed of electrified trolleys however, horsecar companies could expect to double that radius and reap the rewards in real estate. As a result, these companies became intimately involved in urban politics and in many cases bought themselves influence on city councils to ensure they received the necessary franchises. Within a decade, most of the lines had switched over to electric.

For a few more decades, horses were still favored for tasks like fighting fire, hauling waste, and making neighborhood deliveries. But by the end of World War II, even these jobs fell to the automobile. The horse manure problem was solved and the age of the car had begun.

The technological solution

Despite the initial optimism that cars were a clean and efficient alternative to the horse, the new technology has also become a victim of its own success. The burning of fossil fuels generates air pollution that can be as hazardous to human health as the diseases spread by flies, and it releases carbon dioxide that contributes to climate change. A century after the decline of the horse, we are again facing a chronic pollution problem.

Embedded among the engineers and policy faculty of Carnegie Mellon, Tarr has consistently pursued historical questions that provide perspective for contemporary policy debates, particularly the problems of urban waste. But ever since Tarr published that first article on the horse manure problem, commentators have repeatedly used the story as a parable about the wonders of technological fixes to environmental problems. For instance, Steven Levitt and Stephen Dubner used the story of the horse in their 2009 book SuperFreakonomics to justify the use of radical geoengineering solutions to climate change.

Tarr himself doesn’t believe technological change is always a panacea. “Why do we automatically assume that every new device will be better?” he asks. He has made urban technological change one of his specialties because he believes it is important that we understand the drivers of change. “History circles,” he explains.

This particular circle has come around quickly. In Tarr’s office there is a reproduction of a magazine photo hanging prominently amongst the accumulated books and papers; in it stands his father in a worker’s cap, cigarette between his lips, at work under the harsh light of the night shift at a shipyard. He had been one of those workers who built the urban landscape with the help of a living machine. “He had a horse,” Tarr says, “back when he was in the scrap business in New York. He had a horse called Shivers, and that’s just about all I know about it.”

Where to Find Out More

The Horse in the City: Living Machines in the 19th Century by Clay McShane and Joel Tarr Johns Hopkins University Press, 2007.

“The Centrality of the Horse in the Nineteenth-Century American City,” Clay McShane and Joel Tarr, In Raymond A. Mohl (ed.), The Making of Urban America Scholarly Resources, Inc., 1997.

“The Horse Era in Pittsburgh,” Joel Tarr, Western Pennsylvania History, Summer 2009, 28-41


2 thoughts on “HORSEPOWER

  1. Pingback: Morsels for the mind – 17/5/2013 | Six Incredible Things Before Breakfast

  2. Pingback: The Natural & Logical Drains of Pittsburgh | The Blobologist

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