April 5, 2011 will forever be a milestone for the Toyota Prius. It marks the day when Toyota announced one million sales of the Prius in the U.S. It also represents the hybrid's third sales milestone in just six months.

In October 2010, The Toyota Prius hit its first major milestone when worldwide sales topped two-million. It hit its second just last month, when global sales hit three million. That's an increase of over one-million units sold, in only six months! Needless to say, while we're happy to report that the one-millionth Prius has been sold…