my original statement was that the majority of the larger venues were built in the 60's and very early 70's. Ontario 70 was one of them, Phoenix in 69, Michigan 67, Atlanta 60, Charlotte 61, Daytona, 59, Talladaga 69, Riverside late 50's. My point being that these tracks didn't just suddenly appear and take away all of the short tracks. The economy and the popularity of racing back then supported the building of them. More larger tracks were built afterwards sure, but these tracks were built in Big Bill's era for the most part. not all of them he built, but Nascar either did race on these soon after they were built, or raced on them later.