Final answer:
Realigning periods, or political realignments, happen due to factors such as demographic shifts, crises, or dissatisfaction with the political system, leading to a significant change in party support and ideology, such as the New Deal realignment and the shifts during the Civil Rights Movement.
Step-by-step explanation:
Realigning periods, often referred to as realigning elections or political realignment, occur when the existing political order is significantly disrupted, leading to a major shift in political party support and ideology. This can be due to various factors, such as significant demographic changes, major national crises, or widespread dissatisfaction with the current system. One of the most notable examples in the United States is the New Deal realignment during the 1930s, when large numbers of voters began to support the Democratic Party due to the economic policies responding to the Great Depression.
Another prominent example occurred during the 1960s, when the Civil Rights Movement and related social changes contributed to a realignment that shifted many Southern voters from the Democratic to the Republican Party. In essence, realigning periods are often the result of societal shifts, economic upheavals, or transformative events that cause voters to reevaluate their political loyalties and adjust their affiliations to reflect their new priorities and values.