Sure, you might be able to avoid speed cameras with an array of dash-mounted gadgets, but there's also another unseen eye that might be keeping an eye on your speeding habits: your GPS unit. Of course, GPS makers aren't too interested in collecting individual users' data (at least, we hope not), but they are collecting some general data, and TomTom has now released a few of its findings. Most notably, it found that drivers in just about every state stay within the speed limit on average, with only Mississippi edging 0.1 miles per hour over the top speed limit of 70 MPH. Things get a bit more interesting when you get down to specific routes in the United States, however, where the I-15 in Utah and Nevada comes out on top with an average speed of 77.67 miles per hour. On the other end of the spectrum, Washington D.C. proved to have the slowest drivers, where speeds averaged a mere 46 miles per hour -- although that likely has something to do with TomTom's earlier findings that Washington D.C. also has the most congested traffic in the U.S.