http://www.stormcam.org/usa-map/
Where can I find a map showing the climate of the overall annual humidity and dew points across the United States?
I would not a map showing the results day to day, rather one with an annual average.
I could not find one for an average Annual overall, but I found this site: It has http://prism.oregonstate.edu/products/matrix.phtml?vartype=tdmean&view=maps dew points for U.S. per month. Here's another good site: http://www.maps-gps-info.com/us-mps.html This site allows you to "create card" based on many other factors (unfortunately, the dew point / humidity was not one of them), but it may be useful for everything you do. I know this is not exactly what you are looking for, but I hope it will help.
Al Franken Draws The United States Of America