When Noah Webster was busy compiling his dictionary in America in the 1820's he wanted to make a clear break from the British spellings, as the Revolutionary War had occurred and America was now independent from Britain.
This is how we get words that omit the 'u' - flavo(u)r, colo(u)r, etc. As well as centre/centre.
And the 'sation/zation endings that you ask about.
He didn't want to change the appearance/spelling of the word that much but make it distinct as well.
And in the computer age most programs are auto set to USA spellings now.