Donald C. Baumer & Howard J. Gold 
Parties, Polarization and Democracy in the United States [PDF ebook] 

As evidenced in the 2008 elections and the transition to a new era of Democratic governance, one of the most important developments in American politics in recent years has been the resurgence of political parties. Democrats and Republicans represent different world views and policies, citizens recognise these differences, and many of them use party labels to make sense of the political world. Parties, Polarisation and Democracy in the United States describes and analyses the place of political parties in American politics today — both among elites and citizens at large. Many scholars and pundits denounce political polarisation; they view it as a symptom of a broken political system that provides unappealing choices for voters and that is frequently mired in deadlock. Baumer and Gold make a different argument — that party polarisation offers the kind of choice and accountability to voters that was not always present in earlier periods of American political history.