Did anyone actually slow down to 55 MPH in 1974?

I remember that first day on the freeway after the new federal speed limit was imposed, it was most difficult to slow down that much. Just read that during World War II, the speed limit was lowered to 35 MPH to save on gasoline and tires, never heard that mentioned before. Just found that bit of trivia today, reading that fact on-line.

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Pronghorn antelope can run as fast as 60 MPH.

Where was the limit lowered on during WWII? I mean there was no highway system in the country.