How long does a copyright last?

How long after a typeface design is created or released does the copyright last? When is the design available to public domain?

• I know that if we talk about fonts, which is the digital medium that reproduces the typeface, it has another copyright term. But i'm talking about the design itself.

• Answer:

  Typeface designs cannot be copyrighted in the U.S., but the font software that reproduces them can. The names can also be trademarked. So the protections that matter, at least in this country, are copyrighted software and trademarked name.