At North American tracks, races which are run on a turf (grass) course must sometimes be moved to the main dirt course, usually due to heavy rain or other adverse weather conditions; sometimes this switch is made after pick 6 wagering is closed.
In North America, horse races held on grass courses at some tracks may need to be transferred to the primary dirt track, usually because of heavy downpour or other inclement weather; occasionally, this transfer occurs after the conclusion of pick 6 wagering.