How quickly can the nervous system relay messages ?

Many years ago, I read that the speed of communication through
nerve pathways had been measured as 123 meters per second.
I read that roughly around the time that the human race was evolving
nerve cells, and I have no later information.

The first answer posted here is in miles per hour, and when you
go through the unit conversion, it's equivalent to about 120 meters
per second.

This agreement between my ancient information and the new, modern
answer posted today makes me feel that these are both good numbers,
and the truth actually IS somewhere around 120 meters per second.