Replacement of horses by cars in the United States

This week we take a look at the number of horses versus the number of motor vehicles in the United States during the early to middle 20th century. 

At the turn of the 20th century, there were over 21,500,000 horses in the United States, while just 8,000 registered motor vehicles (this includes trucks, buses, and automobiles). In just 30 years the tables had turned. The number of horses had now fallen to just shy of 19 million, while the number of motor vehicles had increased over 3000 times, and was now a staggering 26.5 million, with no sign of slowing down. It took another 20 years for the number of vehicles to double, as well as for the number of horses to halve. 

Now, there are 273.6 million vehicles registered in the United States, roughly 0.8 vehicles per person. What about the equine population? It's actually on the rise. Reports put the American horse population at 9.2 million in 2003, a 33% increase over the 6.9 million reported ten years before.

Source for equine population: Kilby, E.R. (2007). The demographics of the U.S. equine population. In D.J. Salem & A.N. Rowan (Eds.), The state of the animals 2007 (pp. 175-205). Washington, DC: Humane Society Press.

Source for all registered motor vehicles: Federal Highway Administration