This study has attempted to explain the dramatic challenges to the existing party system that occurred in Canada and the United States in the early 1990s. The emergence of new political movements with substantial power at the ballot box has transformed both party systems. The rise of United We Stand America in the United States, and the Reform Party in Canada prompts scholars to ask what forces engender such movements. This study demonstrates that models of economic voting and key models of party system change are both instrumental for understanding the rise of new political movements.