Topps Popeye Tattoo Bubble Gum was released in 1958 and 1966 with similar wrappers differing only in small details and in the indicia (the small text paragraph). How can we identify which is which?
One clue lies in in something called the ZIP code which was first used on July 1, 1963. ZIP is an acronym for Zone Improvement Plan and is a well known scheme in the US to efficiently route the mail. If an address shows a ZIP code, then it necessarily dates from after July 1963 as they did not exist before then.
Here are the two wrappers - one from 1958 and the other from 1966: