Here’s an ambitious online mapping project that combines OpenStreetMap with something called the “latest Highway Performance Monitoring System (HPMS) national highway dataset provided by the Federal Highway Administration.” Basically, it’s all the US highways in the country, shaded by AADT (average daily traffic). Kind of cool to see, and you get a real sense of where all the cars are driving:
Here’s some more info from mapbox.com:
Take a look at the map comparing HPMS (yellow) with OpenStreetMap (blue). You can see that the geographical alignment between the two datasets is on par. The coverage of OpenStreetMap is better, but full road coverage is not the goal of HPMS. We’ve visualized the traffic density attribute in HPMS as line thickness to highlight the regional and national significance of different roads. Thicker yellow lines are more traffic and thinner yellow lines are less traffic. Zoom in to see the numbers for average vehicles per day.
Check out the entire project here.