1. Partisan Polarization in Congress and the Historical Shift in the Bases of U.S. Political Parties I.The Polarization of the American Party System, 1960-early 1980s II. The Regional Shift of the American Political Parties III. The Republican Presidential Majority IV. The Rise and Fall of Split-level Dealignment V. The Polarization of Congress

2. Map 1: Regions Used in This Article

3. Map 2: Electoral College Results, 1876-1956

4. Map 3: 1945-46 House of Representatives by Party (79 th Congress)

5. Map 4: 1948 Electoral College Results

7. Map 6: 1968 Electoral College Results Black = Democrat Humphrey White = Republican Nixon Gray = Independent Wallace

8. Map 7: 2004 Electoral College Results Gray= Democrat Kerry White=Republican Bush Source: http://www-personal.umich.edu/~mejn/election/

9. Source: Congressional Quarterly Almanac 1990, 2005

10. Maps 3 + 8: Comparison of Democratic Majorities of 1945-46 and 1985-86 (79 th and 99 th Congresses) Map 4 Map 8

11. Maps 8 + 9: Comparison of the 1985-86 and 1997-98 Congresses (99 th and 105 th ) Map 8: Democratic Majority Map 9: Republican Majority

12. Maps 9 + 10: The Different Republican Majorities 1997-8 and 1953-54 Map 9: 105 th House Map 10: 83 rd House

13. Source: Congressional Quarterly Almanac 2005

14. Source: Congressional Almanac, 2005

15. Graph 5: Number of Unanimous Votes by One Party against a Majority of the Other in each House of Congress, 1960-2005 Source: Congressional Quarterly Almanac, 2005

16. Map 11: House Seats Turning from Republican to Democratic in 2006 Dark blue = 3-5 Democratic seats gained Light blue = 1-2 Democratic seats gained Source: http://en.wikipedia.org/wiki/Elections_in_the_United_Stateshttp://en.wikipedia.org/wiki/Elections_in_the_United_States