Why does it take 9 loads to bring Sister's belongings to the post office in "Why I Live at the P.O.?"

There are two reasons why it takes nine loads to move Sister's things to the post office.

The first reason is basic and fairly factual. The girl who is helping her is pulling a little wagon, essentially a child's toy. (Welty tells us it is a small wagon just before she tells us it takes nine trips.)

The other reason is that even though Sister is supposedly so upset that she storms out of the house, she is still sufficiently in control of her self that she takes a lot of stuff with her. (This part is not stated openly, but is implied.) That tells the reader a lot about Sister. This is not someone who is really overcome by emotion, or acting on impulse. This is someone who makes a big, dramatic production out of everything, and who is willing to make a girl pull nine loads in a wagon for just a nickle.