NASCAR Racing: OK - Why 42 ?, grid index, starting grid

Question
You explained how the field got from 42 to 43 drivers in each race. But how was 42 decided on prior to that?

Answer
Over the years NASCAR had finally settled on 40 starters at the large tracks but then when they kept having more "big money" teams trying to get into the race then they had starting positions sponsors began to complain and hedge a little about wanting to sponsor a team for a whole season when there was a chance they might not appear in a race. So NASCAR added 2 "sponsors provisionals" to help assure them of the ability to be in every race. That brought the field to 42 and then the "past cahmpions" provisional was added as mentioned in my previous answers.
For a more detailed look at how they got to a total of 43 see:
http://www.nascar.com/2002/news/headlines/wc/03/22/starting_grid/index.html