Why do so many Americans live in mobile homes?

"From the state where 20% of our homes are mobile 'cause that's how we roll, I'm Brooke Mosteller, Miss South Carolina."
 Not the usual jaunty PR message you expect to hear at Miss America. And Mosteller caused a minor storm for presenting what some South Carolina natives felt was a negative slight on the state. A few days after her comments, US Census figures confirmed that her state did indeed have the highest proportion of mobile homes - also known as trailers or manufactured housing - though the figure is closer to 18% than 20%. Mobile homes have a huge image problem in the US, where in many minds they are shorthand for poverty.
 But how accurate is this perception?