AT&T today announced that it has started "doubling the capacity" of its 3G markets, stating that nearly half of all cell sites will receive additional 3G capacity by the end of the year.
The company claims that its 3G mobile broadband network is currently available in nearly 300 major U.S. metropolitan areas, with "plans to expand to nearly 350 by the end of the year."
The map below shows AT&T's current 3G network (in blue). While coverage does indeed cover most major metropolitan areas, large swaths of the country and many states are completely excluded from coverage where EDGE access is plentiful. In the image below, blue represents 3G coverage, while bright orange represents EDGE coverage, and lighter orange represents partner coverage.