Realignment can happen through several mechanisms. Existing voters may convert from one party to another. Younger generations may enter with different attachments. Migration may change the composition of states or districts. One coalition may mobilize citizens who previously participated less. Parties may recruit new leaders, adopt new issues, or lose the ability to contain a conflict. These processes can overlap, so a serious explanation does not assume that millions of voters switched parties on one day.

Temporary movement is not enough. Voters may punish an incumbent party during recession, war, scandal, or an unpopular campaign and then return. A candidate may attract personal support that does not transfer to other nominees. A landslide can therefore be historically memorable without producing realignment. Conversely, gradual change may be real even when no single election supplies an obvious dividing line.

This lesson owns the transformation itself. Ask what changed: coalition membership, issue conflict, geography, organization, or governing dominance. Then test the change across later presidential, congressional, state, and local elections and in the program officials pursue after victory. The New Deal provides strong evidence because group loyalties, policy commitments, and governing control persisted; the South's later partisan transition shows that the same kind of structural change can unfold gradually. Dealignment is different because attachment weakens without necessarily moving to the opposing coalition. A critical election, discussed next, is the focal contest associated with a transformation; realignment is the durable pattern that the wider evidence establishes.

Video lesson: Party Systems: Crash Course Government and Politics #41