Las Vegas 250

The Las Vegas 250 is a motocross event that Chuck Greene attended right before the Las Vegas Outbreak. The grand prize is $250,000, and the winner takes all.

Speculation
(Once somebody gets a hold of the actual issue 3, please edit the top part.)

However, before the race could end, Harjit Singh and Phenotrans Mercs unleashed a swarm of Queen Bees that infected everybody attending the event with the zombie virus. It is shown as ground zero of the outbreak.