[pawpawdiv9]

To answer your Nascar question:

Best Answer: Back in the old days of NASCAR, there were some tracks where there were no limits, such as Darlington (as many as 75) and Daytona (in the 50's many times). Over the years the size sort of evolved. It was 40 for the large tracks and 32 for the small tracks in the late 70's and early 80's. Then if was 42 for large and 36 for the small/short tracks. Then the champion's provisional took it to 43 and NASCAR made 43 universal at all tracks including thee small/short tracks, like Bristol. As good explanation is at NASCAR.com:

NASCAR started playing with the size of the fields five or six years ago. Different tracks used to start different amounts of cars in each race depending mainly on how many pit stalls the track had available to use. NASCAR wanted to standardize the size of the fields and after some trial and error, settled on a field consisting of 36 qualifiers with six provisionals that could be used by the regular drivers. That's a total of 42 cars.

The story about the odd car, the 43rd starter, began about twelve years ago when Richard Petty was having trouble making the starting lineup. NASCAR created a Champions Provisional to help get Petty into the field. In fact it could be used to help any present or ex-champion but just recently was used for other drivers, if a Champions Provisional wasn't used. It goes to the car owner with the highest points that didn't qualify on speed.

NASCAR was happy with the standardization and stuck with that number even though some drivers had to share pit stalls at some tracks before they were brought up to the present standards. They could run more at some tracks and they probably should run fewer cars at others, but it's a standard 43 cars now

The first Southern 500 in 1950 had 75 entries and the following year it had 82 or 83 and took 6.5 hrs to complete. Imagine if we had that now a days? That would be wild!

Prior to the modern era of NASCAR(mid 70's) the NASCAR fiels had anywhere from 16 cars(1/4 mile tracks) to 60 plus cars on large tracks(Talladega-Daytona-Road corses).
With the startof the modern era different amounts of cars were used,34 or 36 on the half miles and 45 on the large tracks.The adding of provisionals to the quailifing list .the number was set at 43 to fit all tracks.
Most people say because this was Richard Petty's number butit was a random number chose by NASCAR