Midterm elections brought larger power swings in past

By Tom Emery

With the nation sharply divided, Congressional majorities have been slim in recent years. The power struggle helps lead to the overkill of attack ads that we’re all tired of.

Congressional balance of power, though, has not always been so close. Both the Democrats and Republicans have enjoyed huge majorities at one time or another, and some midterm elections have brought staggering shifts of control.

In the period before the traditional two parties of today, the Democratic-Republican Party dominated the first third of the 19th century, holding enormous margins in both houses. Never...