Maybe I got real lucky but I went to a NCSU FB game during the fair and even showed up late and traffic was OK. It was around 79.
In 1979 it wasn't even a little bit of a problem. It wasn't a problem in the 80s either for the most part. It was the mid 90s when it got bad ... and then worse. The city grew, the fair grew, and then the arena construction (and eventually the building) actually made parking for football more spread out and difficult ... by the end it was a nightmare.