Political parties are an essential and often puzzling element of American politics. They consist of individuals with varying degrees of attachment to a party trying to gain representation of their concerns. Officeholders and prospective officeholders hope to attract enough voters with diverse concerns so they may control government. Although this interaction seems simple, parties are often puzzling. They pursue policies and constituents in ways that often leave us wondering: Why are they trying to advocate for specific groups and win their votes? Why are they supporting a position that we might think does not make sense? Why are they pursuing a particular strategy in a particular election cycle? Then about the time we figure out these various interactions, something changes, leaving us puzzled again.

At various points in our careers, each of us has experienced such puzzlement. We also share the experience of reading James Sundquist's The Dynamics of the American Party System and finding the book enormously helpful in providing a broad overview of parties and their constituencies and why both changed over time. Sundquist wrote the book in the 1970s, a time of enormous change in American political parties. Each party was seeking and incorporating new constituencies and changing its bases of support. He finished that book at a time when it was very difficult to see where that change was headed. It is now clearer.