NASCAR Racing: rain shortened race, lap race, possiblity

Question
How many laps have to be ran to make a race an official race if the race is called due to rain.

Answer
Hi Scott,

  According to the offical rulebook, a race must reach halfway before it can be called offical.  So if its a 300 lap race, the leader must start lap 150 before rain can offically end it.
  If rain starts earlier, then it is a possiblity that NASCAR just stays another night and pick up right in the order they have to stop...some of the best races end on a monday afternoon.
 Hope i helped!
 Coy Jordan