In 2006, the Democrats picked up 30 House seats. This year, they are slated to pick up anywhere from 15 to 30. Those numbers hold some pretty historic potential. Here's CQ:
The last time a party made a net gain of 15 House seats in consecutive elections was when the Republicans did it in 1978 (15 seat gain) and 1980 (34 seat gain). No party has made a net gain of 20 House seats in consecutive elections since the Republicans accomplished the feat in 1950 (28 seat gain) and 1952 (22 seat gain).
In the Senate, Democrats are poised to pick up anywhere from five to 10 seats. The last time the Senate saw movement like that was 1980, when Republicans picked up 12 seats and Ronald Reagan took the White House. CQ notes that the 19th century saw far more volatility in both chambers, but particularly the House. "It's less common today to see huge seat swings because of demographic shifts and a surgical precision in redrawing congressional district lines to create politically "safe" seats for both parties." Can you imagine what next Tuesday would look like if politicians couldn't gerrymander their way into near lifetime appointments?