Although it may sound vaguely like the title of a Stephen King novel, the mallwalkers are, in fact, no work of fiction. Every morning, during that period of capitalistic limbo in which the doors to the mall are unlocked but the stores are not yet open, one may find a surprisingly large number of elderly people speedwalking their way around the inside, through eerily silent passages flanked by iron bars, many of them dressed up in windbreakers and jogging pants.
Many of them appear as though they could break their frail little bones simply by sitting down too hard, yet they keep up a pretty good pace.
I first encountered these people during my high school years, when I worked at a Cinnabon. Upon coming in for my first morning shift, I was utterly baffled. Sure, you see people shuffling around mindlessly through a mall any time you enter its seductive confines, but usually they're consumers. A co-worker explained it to me and I got quite a kick out of it, sometimes coming in a few minutes early for work on subsequent days to walk a few laps myself or ride my bike (the mall security guards didn't seem to do much at this time of the day aside from unlocking the doors) alongside them, sometimes receiving a few glowers from the more ardent mallwalkers, who take the whole thing quite seriously.
Since then, anytime I've been through a mall in any part of the country before opening, I've seen these people. It's a nationwide thing, I guess. Maybe even a cult. | 
