Over the Christmas holiday Lisa and I drove to (hometown) Raleigh, NC. We got on I-95 and I noticed the type changed between Savannah to Charleston. I did some looking and found out the Federal Highway Administration (FHWA) is set to replace all guide signs on roads with this new type. Its called Clearview. (wiki) Check out FHWA's statement and guidelines for use of Clearview here (officially approved Sept 2, 2004).

I also found a great article on the New York Times about the replacement of Highway Gothic to Clearview, read the article here. (below: Highway Gothic, left; Clearview, right) 
photo Don Meeker

Clearview comes in 7 positive contrast styles (that is light text on a darker background) and 6 negative contrast styles (that is dark text on a lighter background).
Conceptual applications
Another great blog post at cartype.com about Clearview.

Buy the Clearview family at clearviewhwy.com or here at Terminal Design.
Designers attributed with Clearview: Donald Meeker, James Montalbano, Christopher O'Hara, Martin Pietrucha & Philip Garvey