Divided government in Washington DC has led to vetoes, filibusters and held up confirmation of nominees amongst other things. This excellent research from the Pew Research is therefore rather fascinating. The top link above will take you to a quiz to show where you stand personally in the spectrum of US politics. The results compare your views to the general public and is very interesting in terms of the polarisation of US political opinion.
The second two links look at some of the data behind this analysis, showing who each group is most likely to vote for (in the second link) and how the average Democrat or Republican voter has changed since 1994 (in the third link). Both are outstanding evidence for use in any Unit 4 discussion of bipartisanship or the lack thereof, as well as for Unit 3 Elections and Parties topics.