Willis Carrier's Machine Remade the South, and Made the Case for Cheap Energy

The most important political invention of the twentieth century was not a weapon, a vote-counting machine or a tax form. It was a box that blows cold air. And I will go further: if you want to know who did more to change where Americans live, work and sleep, you will have to compare the congressman with the engineer, and the engineer wins on points.

His name was Willis Carrier. He was trying to solve a printing problem. He ended up solving summer. Let me tell you the story, because it is a better argument for abundant energy than any white paper I could write, and because every time someone proposes to make electricity scarcer and dearer, they are proposing to take something away from somebody's grandmother in August.

The Man and the Problem

Willis Haviland Carrier was born in 1876 in upstate New York and trained as an engineer at Cornell. After graduating he went to work for the Buffalo Forge Company, which made heating and ventilating equipment. That is the career of a practical man who liked to make machines work, and the story should stay at that level. He was not a visionary prophet. He was a problem-solver, and the problem that landed on his desk was a very specific one.

A printing company in Brooklyn, the Sackett-Wilhelms Lithographing and Publishing Company, had trouble in the summer of 1902. In those days a colour print was made by running the same sheet of paper through the press several times, once for each colour of ink. Paper takes on and gives up moisture from the air, so on humid days it swelled and on dry days it shrank, and the colours would not line up. The pictures came out blurred, the company lost money and the customers complained.

Carrier was asked to fix it. He designed a system that passed air over coils chilled with cold water, which cooled the air and, by condensing out moisture, dried it. Control the air, and you control the paper. He submitted the drawings in July 1902, and the purpose was the humidity, not the comfort. Cooler air was a by-product, a happy accident that nobody at the printing plant had asked for.

That is a nice detail to keep in mind. The greatest comfort technology of the century began as an industrial solution to a business problem, solved by an employee who had a good idea and a company willing to try it. Nobody passed a law. Nobody ran a program. A customer had a problem, and a man got paid to solve it.

The Patent and the Science

In 1906 Carrier received a patent for an "Apparatus for Treating Air," which described a way to control the humidity of air by spraying water in a chamber and controlling the temperature of the spray. It is what people now call the foundation of modern air conditioning. He kept improving it. In December 1911 he presented a paper to the American Society of Mechanical Engineers setting out what he called rational psychrometric formulae, the mathematics relating the temperature, the moisture and the energy content of air. Engineers still use the same ideas in the field. In 1915 Carrier and a handful of colleagues founded their own company, the Carrier Engineering Corporation, to sell the product.

I want you to notice what drove this. It was private enterprise: a customer with a problem, an inventor with a solution, a patent system that protected his right to profit from it, and a company founded by people who risked their own money. The Constitution, in Article I, Section 8, Clause 8, gives Congress the power "To promote the Progress of Science and useful Arts, by securing for limited Times to Authors and Inventors the exclusive Right to their respective Writings and Discoveries." That clause is why Carrier had the protection he needed to build a business. The Founders understood that the way to encourage invention is to let the inventor profit by it.

From Factory Floor to Movie Palace

At first air conditioning was for industry: textile mills, tobacco factories, printing plants, food processors, places where humidity and temperature spoiled the goods. Then it crossed into public life, and the place it crossed into was the movie theatre.

Before air conditioning, theatres in the summer were a problem. A packed hall in July was close to unbearable, and many shut down for the season or lost most of their business. Cooling changed the economics. Theatre owners began installing the systems in the 1920s, and a few well-known houses advertised themselves with big banners reading "Cool inside." One of the most famous early installations, the Rivoli Theater in New York, got a Carrier system in 1925, and the story goes that crowds came simply to get out of the heat. Whatever the exact numbers, the trend is clear: an industry that had treated summer as a dead season discovered that it could be the biggest of the year.

That is the origin of the summer blockbuster. Studios saved their big pictures for the warm months, because they now had an audience that wanted somewhere cool to sit for two hours. Every time you buy a ticket to a summer movie you are paying tribute to a printing problem in Brooklyn.

The same went for stores, offices, hotels and trains. Congress itself got air conditioning in the late 1920s, a fact I can only describe as ironic, since some of the same Washington has since spent decades telling the public to use less of it.

The Sun Belt

Now the part that changed the map. For most of American history, the South and the Southwest were hard places to live in summer, and economic and demographic gravity pulled toward the cooler North. Heat and humidity shaped the way people built, worked and rested: high ceilings, deep porches, siestas, a slower tempo in the hot months. Businesses hesitated to locate where workers could not be productive for much of the year.

Residential and commercial air conditioning, which spread widely after the Second World War as machines got smaller and cheaper, changed that. Offices could be cool in Houston. A factory could run in Atlanta. A retiree could settle in Phoenix. The phrase "Sun Belt" was popularised in 1969 by the political analyst Kevin Phillips, in his book on the changing political geography of the country, to describe the swath of states from the Southeast to the Southwest that was growing in people and political weight. The population shift of the second half of the twentieth century toward the South and West is one of the largest internal migrations in American history, and it would have been very different without cheap cooling.

I want to be careful here. Air conditioning was not the only cause. Defence spending, the interstate highways, lower taxes, right-to-work laws, the oil and gas industry, the aerospace industry and plain job opportunity all drew people south and west. But it is hard to find a historian who would deny that without cooling the movement would have been far smaller. A modern Sun Belt is a machine-made climate.

Heat Kills, and Cooling Saves

Now the argument for abundance gets a little more serious. Heat is not just an inconvenience. It is dangerous, especially for the old, the very young and the sick. Before air conditioning, summer heat waves killed people in large numbers, and every city had its stories of the season's worst days.

There is serious research on exactly this. A team of economists, Alan Barreca, Karen Clay, Olivier Deschênes, Michael Greenstone and Joseph Shapiro, studied the relationship between temperature and mortality in the United States across the twentieth century. They found that the death rate on very hot days fell dramatically from the early 1900s to the early twenty-first century, that the mortality impact of very hot days fell by about three quarters, almost all of it after 1960, and that the spread of residential air conditioning explains essentially all of that decline. I give you the direction and not a precise figure, because I want you to read the paper in the Journal of Political Economy, 2016, rather than rely on my summary. But the conclusion is the one a sensible person would expect: people who can cool their homes are much less likely to die in a heat wave.

Set that beside the way policy discussions about energy are framed. When people talk about heat, the conversation turns quickly to emissions and to the idea that we should reduce cooling demand. They rarely say, in the same breath, that cooling has saved a very large number of lives. That is the other side of the ledger, and it belongs in the argument.

The Argument in Numbered Form

1. Abundant energy is a good, not a vice. Cheap, reliable electricity has made it possible to live safely and productively in places that were once punishing.
2. The benefits are concrete. Fewer heat deaths, more productive workplaces, entertainment industries, regional growth and comfort for ordinary families.
3. The cost of scarcity falls on the vulnerable. The wealthy can cool a house at any price. The poor, the old and the sick are the ones who suffer when power is rationed or dear.
4. Policy that raises the price of electricity is a policy that raises the price of safety. It should be judged accordingly, and with open eyes.
5. The right response to the need for cooling is more and better supply, not less demand by decree. Efficiency gains are welcome when they come from innovation and from consumer choice, as the history of the air conditioner itself shows.

That last point deserves a moment. Today's air conditioners deliver far more cooling per unit of electricity than the ones of a generation ago. A good part of that came from competition and engineering, and a good part from federal efficiency standards. I will not say the standards did nothing. But the engine of the improvement was an industry that wanted to sell a better machine. When efficiency is demanded by customers, it comes quickly. When it is dictated from above, it can cost more than it saves and arrive with fewer choices. For the broader story on how Washington reaches into the home appliances you buy, see Low-Flow Toilets and Banned Bulbs, How Washington Moved Into Your House.

The Strongest Objection

The best argument against the celebration is environmental. Air conditioning uses a great deal of electricity, and in places where that power comes from fossil fuels, it adds to emissions. The old refrigerants were also harmful, and the phase-out of those chemicals showed that a cool house had a price on the sky. A world that is warming will want more cooling, which means more energy, which means more emissions. So perhaps we should be wary of building a civilization that depends on a machine that runs on a power plant.

That is a fair concern. Let me give it a fair answer in order.

First, the right response to a carbon concern about electricity is cleaner and cheaper electricity, not less comfort. Nuclear power, natural gas and hydro all produce power without the heavy emissions of older plants, and nuclear in particular is a serious answer, a point made in Count Deaths per Unit of Power and Nuclear Beats Nearly Everything Else. The goal should be to make the supply cleaner while keeping it abundant. Second, the refrigerant problem was solved by engineering and by an international agreement, and the industry found substitutes. That is a record of problems being met, not of a technology being abandoned. Third, the choice is not between air conditioning and a pristine world. It is between air conditioning and a hotter, deadlier summer for the people who cannot afford alternatives. Fourth, the people who lecture the rest of us on the sins of cooling are generally not the ones who go without.

If the price of a livable summer were set by politicians who had never had to choose between a bill and a fan, it would be set too high.

The Grid and the Future

There is a practical lesson as well. The same grid that cools a house on a ninety-five-degree day in Texas must be able to deliver power at the hour of greatest demand, late afternoon in summer. That requires generation that can run when called, a transmission network that can move power to where it is needed and a regulatory system that allows both to be built. For how the permitting maze has turned building into an ordeal, see We Raised the Empire State Building in About a Year, So Why Not a Power Line. And for how fragile an under-built system can be in a crisis, see Seven Things People Said About the Texas Blackout of 2021, Tested.

There is a quiet moral point here, too. We are told that energy abundance is something to feel guilty about. The story of Willis Carrier says the opposite. He did not set out to make the world a worse place. He set out to solve a problem, and in doing so he saved lives, enriched a region and gave millions of people a better afternoon. That is what good energy does.

The Case in Brief

1. Willis Carrier's first system, designed in 1902 for a Brooklyn printing plant, was meant to control humidity, and he received his patent for treating air in 1906.
2. Cooling spread from factories to movie theatres and public buildings, creating the summer film season and, after the Second World War, helping to make the South and Southwest livable year round.
3. Research by Barreca and colleagues found that heat deaths in America fell sharply over the twentieth century, with residential air conditioning explaining essentially all of the decline in hot-day deaths.
4. Abundant, affordable electricity is therefore a matter of safety and prosperity, and policies that make it scarce fall hardest on the old, the poor and the sick.
5. The answer to the environmental objection is cleaner, abundant supply, not rationed comfort.

What you can do: Look up your electric utility's next rate case on your state public utility commission website, and file a comment asking that reliability and affordability be weighed alongside every new surcharge.