'Big Wave' Midterm Elections Come in Three Shapes  Source
Organization: Pew Research Center  11/01/2006 - In recent
decades, there have been three basic ways that turnout has
worked to produce the sort of "big wave" midterm election
results that the Democrats are hoping for next week, according
to analysis by the Pew Research Center.  First is the "one-party
surge," where one of the parties significantly increases its
vote from the previous midterm while the other party's vote
remains essentially unchanged. That is what happened in 1994,
when Republicans won control of both houses of Congress. The
nationwide GOP congressional vote spiked by more than 9 million
votes from 1990, the biggest increase in one party's vote from
one midterm to another since World War II. Meanwhile, the
Democratic total declined by 400,000 votes.  Another way to
produce a big change in Congress is a "one-party collapse,"
where a huge number of voters from one of the parties simply sit
out the election. That is what happened in 1974,