Because the US Government is a very large actor in the US economy, and because many of the same principles that apply to analyzing economic cycles applies to politics as well.
Maybe Ron Paul was on to something (9/30/08)
Is the North rising again? (10/16/08)
Crony Capitalism still Reigns Supreme (4/20/09)
The New Deal’s great mistake (5/3/09)
David Brooks backs up the Dynamist (9/18/09)
The GOP Will Not Repeal Obamacare (3/23/10)