Since 2002, about 18 percent of congressional seats have changed hands (that is, a D and an R have held the seat). Jason Kelly and I have a paper on this that we will post once we incorporate the 2010 election results.  As far as I can tell, the seats that changed hands were proportionally distributed among partisan and bipartisan gerrymanders. For every successful bipartisan gerrymander (e.g., California) there were others that were less successful (e.g. New York). Same is true for partisan gerrymanders (compare Florida with Pennsylvania).  

I guess one could say that gerrymanders become more unstable over the course of a decade, all else equal. But each decade seems to differ from the last. Compare the 2002 and 2004 elections with 1982 and 1994, for example.

I would say (perhaps inviting controversy) that absent intentional efforts to draw competitive districts, it might be difficult to draw more than about a third of House districts that would be likely to change hands throughout the decade.  However, a lot could happen in terms of shifting party ID over the next ten years. 

Sent from my Verizon Wireless BlackBerry

-----Original Message-----
From: Douglas Johnson <djohnson@ndcresearch.com>
Sender: election-law-bounces@mailman.lls.edu
Date: Fri, 29 Oct 2010 14:46:29 
To: <rick.hasen@lls.edu>; 'Election Law'<election-law@mailman.lls.edu>
Subject: Re: [EL] Redistricting answer

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