One of the things that triggered my asking this question was an entry in "Gettysburgs Bloody Wheatfield" by Jay Jorgensen. The entry has a notation as being copied from McLaws "Gettysburg".

This excerpt is from Jorgensons chapter two and is describing a hurry up and wait scenario in which McLaws Division was waiting to get closer to the action at Gettysburg on July 1, 1863 at around 8:00 AM.

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"..............., he recieved orders to permit Major General Edward Johnson's Division of Ewells Second Corps to proceed first. When the last of Johnsons infantrymen had passed, McLaws was again deined access to the road, this time by Ewell's wagon train. The fourteen mile long train finally finished passing around 4:00 PM."
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I dont know if the 14 miles long was an exaggeration or not but that must have been hundreds of wagons if so. This many wagons would have needed many hundreds of draft animals to be cared for at all times too.