HTC EVO 4G : Way To Clear Website Showing 4G All Around DC / Baltimore?

I used 20810 and got real specific map showing 4g and then entered a bunch of Columbia and Baltimore zip codes and while the map did not show specific coverage zone shading areas, I was offered the opportunity to sign up. I picked random zips up and down I-95 and there seemed to be coverage offered most everywhere on the westen shore until you start down towards St Mary's. Eastern shore also came up dry, as did Frederick itself.