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).
Designers attributed with Clearview: Donald Meeker, James Montalbano, Christopher O'Hara, Martin Pietrucha & Philip Garvey