posted on Jun, 28 2009 @ 04:50 AM
I understand your question and am sure I've also seen those different spellings used at various times.
As to why Americans seem to spell it differently occasionaly, I have no good answer. Possibly for the same reason that they removed the "u" from
numerous words such as "neighbo(u)r", "colo(u)r", "tumo(u)r", etc ... changed the calendar dating format from day/month/year to month/day/year
... and changed the pronunciation of many words e.g tumour that was pronounced tyoomor into toomor.