At this years fair, a WI couple that drove a 6-horse hitch in competition offered an exhibition of driving a team of 10 after the competition was complete.  This means 10 horses are harnessed to drive a wagon.  There was no hesitation to accept the exhibition offer.

The couples instructor is in his 70's.  The guy has been driving for 15 years, and she (not in the video) has been driving for around 9 years.

The narrator of the video, who was also a competitor in the 6, and lent two of his white horses to help make up the 10.  It was explained that controlling 10 horses is quite a talent.

It was quite a treat to see.