Are there good sources for record sales at the time of release?

I was thinking about old music - Sinatra, Elvis, the Beatles, etc. We do a lot of reporting by sales numbers. And in threads where they are discussed, the songs that have longevity win out. But I was wondering if there were any sites that might have information about popularity at the time they came out. Maybe how popular they were (or how many sold, as single or album) in the first year or two.

I’m just interested in contemporary popularity. And, too, I think fleeting or ephemeral popularity doesn’t necessarily indicate inferiority. Some things aren’t meant to last forever, and that’s okay.

Billboard magazine, perhaps?

Yeah. Billboard, along with Cashbox and Music Vendor/World are the holy trinity for that sort of thing going back to the 1940s. Do a search on any record and the name of one of these magazines and you’ll find what you are looking for. Be careful of Cashbox, since a lot of their rankings are based on jukebox plays and they will combine different versions of the same song into one ranking.