Preface. Before the industrial revolution there were only four sources of mechanical power of any economic significance. They were human labor, animal labor, water power (near flowing streams) and wind power. Work done by animals, especially on farms, was still important at the beginning of the 20th century and remained significant until mid-century, when trucks and tractors displaced horses and mules (Ayres 2003).
Just as horses were indispensable the past millennia, so have the cars and trucks of the 20thcentury become essential to our way of life. If one horsepower equals the power one horse can generate (this is roughly true), then the 268.8 million cars and trucks in the United States, let’s say with an average horsepower of 120 HP, then that’s nearly 32.3 billion horses. If each needs an acre of pasture, then that’s over 50 million square miles of land. But the U.S. is only 3.5 million square miles. Clearly we can’t go back to horses – except we have to at some point because oil is finite (I’m assuming you’ve read my book “When Trucks Stop Running: Energy and the Future of Transportation” to understand why biofuels, CTL, batteries, overhead wires, natural gas, and hydrogen can’t replace petroleum powered internal combustion engines).
Eric Morris. April 1, 2007. “From Horse Power to Horsepower”. Access Magazine, University of California.
The horse was the dominant mode of transportation for thousands of years. Horses were absolutely essential for the functioning of the 19th-century city—for personal transportation, freight haulage, and even mechanical power. Without horses, cities would quite literally starve.
From 1800 to 1900, US per capita GDP rose from $1,148 to $4,676 (in 2000 dollars). This meant greater trade, and virtually all goods were, at some point in their journey, transported by horse.
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