Sam, he was sometimes in the back of the wagon.

He had been more'n half asleep all afternoon, but now it was night he was waked up, the way niggers and cats will do, and every once in a while he would get out behind and cut a few capers in a moonlight patch, jest fur the enjoyment of it, and then run and ketch up with the wagon and crawl in agin, fur it was going purty slow.
The ground was sandy in spots, and I guess we made a purty good load fur Beck, the old mule.

She stopped, going up a little slope, after we had went about a mile from the Witherses'.

Sam says he'll get out and walk, fur the wheels was in purty deep, and it was hard going.
"Giddap, Beck!" says the old man.
But Beck, she won't.

She don't stand like she is stuck, neither, but like she senses danger somewheres about.