[pcrh]

Eyeballing the chart in the OP and the French data shows them to have a comparable pattern. While OP's data is horses per person, and the French is total number of horses, both show a decline in horse numbers starting about 10 years after widespread adoption of the motor vehicle and falling to 50% of their peak in the mid- to late-1950's, with the French data being perhaps a bit over 5 years delayed compared to the US data. That is, it took 25 to 30 years after mass production of automobiles was started by Ford for 50% of "horsepower" to be replaced.

The point isn't to claim that motor vehicles did not replace horses, they obviously did, but that the replacement was less "sudden" than claimed.

[hn_throwaway_99]

> That is, it took 25 to 30 years after mass production of automobiles was started by Ford for 50% of "horsepower" to be replaced

I just googled "average horse lifespan", and the answer that came back was, exactly, "25-30 years". There's a clue in that number for you.

[pcrh]

Yes, I considered that. Someone using a horse-drawn wagon to deliver goods about town would likely not consider buying a truck until the cart horse needed replacing.

The working life of a horse may be shorter than the realistic lifespan. Searching for "horse depreciation" gives 7 years for a horse under age 12, the prime years for a horse being between 7 and 12 yrs old, depending on what it is used for.

I'm willing to accept the input of someone more knowledgeable about working horses, though!