On Sat, 22 Oct 2016 16:45:34 +0100, Bod wrote:

Anu ideas why the USA hasn't changed to the Centigrade system?
Only a handful of countries use fahrenheit today.

Centigrade makes a much more logical system.
Centigrade: 0C is freezing and 100C is boiling.

If the only thing you are interested in is the state of distilled
water at sea level, I agree C is better. I use it in scientific
measurements regularly too but there are 50 million Americans who do
not want to be confused by two systems and it would take a while to
get them all switched over.
To start with we would need to buy about a billion new thermometers,
then learn what 30c means when we see that is what the pool is at.
There is also that issue of how precise F is compared to C without
resorting to fractions of a degree, mentioned above.