Three things may have happened:
3) The number of votes for any one song from before 1964 was simply not enough to get it into the countdown. Oldies, do the math. A listener who was 16 in 1964 is 65 now. So the bulk of pre-1964 votes for songs that are people's all-time favorites are likely to come from people older than that. Factor in death, infirmity, the lack of comfort with navigating the CBS-FM website and casting a vote, and there's no way that group of people doesn't get crushed by the 35-55 year olds who are alive, well and participating.
CBS-FM doesn't have to delete any votes for this to happen...it's just the passage of time.
True...Didn't think of that. Maybe if the countdown was the top 1000, then possibly a few pre '64's may have made the lower portion. It'll be interesting to see how KRTH's plays out here soon.