If you can find the total or per capita miles driven in 1923, I think that would make the data complete. But it seems quite clear pedestrian deaths are vastly lower now than in 1923.
[1] https://www.cdc.gov/motorvehiclesafety/pedestrian_safety/ind...
The figure in the article is similarly reporting all automotive fatalities.
https://en.m.wikipedia.org/wiki/List_of_motor_vehicle_deaths...
I clearly wrote "pedestrian/car deaths" and linked to a source that clearly explained it. I'm not sure how else to put it.
Here's a better answer [1]: 21 fatalities per 100M vehicle miles of travel in 1923 to 1.36 in 2007. That should completely answer the request for a source.
[1] https://www.fhwa.dot.gov/policyinformation/statistics/2007/p...
[1] https://www.fhwa.dot.gov/policyinformation/statistics/2007/p...