Dating postcards postage
It was common for early postmasters not to bother including the year in the date, no doubt assuming that the customer knew what year it was.
There is some confusion on what Real Photo Postcards (RPPC) are, and how to differentiate from a printed postcard.
Does your card have the words "Private Mailing Card, Authorized by Act of Congress on May 19, 1898" on the back?
The words "Post Card" were not printed on postcards until December 24, 1901.
It is of course possible to find undivided back cards used after 1902 and divided back cards used with older (pre 1902) stamps Stamps for King Edwards reign were issued on 1st January 1902.
The inland postage rate for postcards was ½d (halfpenny) throughout this period.