Those two old pics were taken in front of the Tulsa Expo Center. I grew up in that area and recognized it immediately. You can even see the leg of the Golden Driller in the top right corner of the 2nd pic.
OK...I know - REAL late to the party, but I was just directed to this photo and this thread from a link over on FBBO.
Anyway, yes, this is in Tulsa, the occasion was the 76 Street Machine Nationals. I've seen several images from that event in this thread, as well as some other 'Nats' pictures; thanx! Really enjoy em.