I was vaguely aware of the following statistics but these figures are even worse than I thought. High profile races like the Presidency and Senate get a lot of notice and press but I wonder what percentage of the electorate actually participates in House races and more local elections (city, town and state offices)? This is from Political Wire: A Travesty of Democracy:

The Economist notes that "if democracy means multi-party competition at the
grass roots, America is not a full democracy in elections to the House of Representatives."

"The sheer uncompetitiveness of most House races takes one's breath away. In 2002, four out of five of them were won by more than 20 points. The average margin was a stunning two to one, meaning some races had even bigger margins. Last time, 200 races had margins of 40 points of more and 80 were uncontested. So far this year, the uncontested figure is 68. In 2002, just four incumbents lost to challengers at the polls (another four lost in primaries). North Korea might be proud of the incumbent re-election rate: 99%. More than nine in ten Americans live in districts that are, in practice, one-party monopolies."