Until tonight, the explanation of, "Mama has to work late" has been sufficient... that is she accepted my answers to "why?why?why?". Tonight she needed more detail, so this is what I came up with...
There is a plant in Mexico (eraser) that makes parts to build a car. It ships the parts by train (train) to a plant that puts the cars together (black box). There was a flood and the river swelled and broke the bridge (note broken bridge). It was too dangerous for the train to go on the tracks...
So Mama and her friends have to figure out other ways to get the parts to the car plant. They use other trains, planes, and trucks to move the parts before the plant gets shut down...
I left out the part about the banditos robbing trucks at the border... all I had left was Mrs. Potatohead and it wasn't to scale.