Flowing Data has an awesome illustration of the Wal-Mart stores of the course of the last 50 years. Starting in 1962 in northern Arkansas, Wal-Mart crept into the surrounding area, opening new stores slowly at first, but its growth sped up with time. By 1998 there was a Wal-Mart in every one of the 50 states and the pace of expansion has only picked up since then.
It’s still a work in progress, showing a limited number of international locations (some in British Columbia, Canada and one in Cape Town, South Africa), which I know to be incomplete sample, having been to a Wal-Mart in China myself. Obviously, this is a result of incomplete data, which can be quite difficult to obtain (I’m actually impressed that any international locations are shown).
Regardless, it’s worth a look.