Broadband Map for the United States
The National Broadband Map has some neat maps. For instance the speed test one shows that real speeds are slower than advertised ones in my area (but surprisingly in some areas they are actually slower than real speed).
The website is lacking a map of the percent of people who have broadband. Which is weird. I recently learned that around 41% of Philadelphians lack home broadband access which is due to poverty. You could try to have a public internet system, but it would be tricky to run it. For a while Philadelphia was considering a public wireless plan, but my impression is that wired is much more likely to work inside houses and not have coverage issues.