Surprise-surprise the TC is wrong. I KNOW I went into the current location in the mid-80s.
The date is included in this old article. I know it was way earlier than 1990 as I've been going there since my daughter was a toddler.
The downtown branch is wasting an awful lot of space right now. Half of the main floor is a storage/jumble area. All the magazines are gone, all the old issues of magazines are gone. We checked out tons of magazines and really enjoyed reading the old Illustrated London News. Not everyone wants to read current magazines online. I don't and not everyone has a device to do so. The amount of books they toss out is criminal.