A glimpse into the growth of Wal-mart provides an eye-opening view of their saturation of the retail market (via the boxtank ) as presented by economist Thomas J. Holmes  of the University of Minnesota as a movie [windows media] .
The movie was a companion to a working paper called The Diffusion of Wal-Mart and Economies of Density [pdf] .
On a lighter note, remember in the tv trailers advertising the Fox show called The Simple Life  a few years ago, when Paris Hilton thought Wal-mart was a store to buy walls? .
Wal-mart’s dominance has been long controversial in small town America as downtown areas have often fought to protect their central business districts by keeping them out. Wal-Mart has become the posterchild for this movement, especially after small towns grew dependent on the tax revenues the stores generate  and put suppliers in a pickle .
With the gaining momentum of new urbanism  and the revitalization of downtown areas by converting obsolete commercial buildings into residential, the entry of big box stores like Wal-mart are believed by many to disrupt the natural economic evolution of downtown residential centers, or stop them all together. With the saturation of Wal-mart stores, it would appear likely that there will be new pressures for them to develop in urban areas, but this will likely add to their current public relations woes [Newsweek]  as they attempt to remake their public image [NYT] .