why does Nascar , Indy 500 etc. always go counter-clockwise

[pianoplunker]

I was just curious if there was some reason for it. I am not a racing expert but it seems like the big races are always counter-clockwise.

[indianajo]

In the US, driver's seats are on the left of the vehicle.  If the vehicle oversteers, that is the rear end steps out, the sight line decreases in angle from straight ahead, instead of increasing, if the circuit is counterclockwise.  Vehicles on dirt tracks, the training ground of these drivers, tend to oversteer quite frequently.
Furthermore, engines turn counterclockwise viewed from the driver' seat.  This lifts the right rear wheel on high power takeoff.  Turning left shifts the weight of the vehicle to that wheel, making the vehicle faster on left turns if enough power is used to spin the wheel.