HISTORICAL ELECTORAL VOLATILITY AND INSTITUTIONAL STABILITY The U.S. has experienced four major realignments since 1860—1896, 1932, 1964, and arguably 2016—each triggered by economic crisis, demographic shift, or ideological rupture. Modern polarization metrics show affective polarization (emotional hostility across party lines) has tripled since 1978, while straight-ticket voting has climbed from 65% in 1992 to 84% in 2020. These patterns suggest institutional stress: when coalition loyalty becomes rigid and swing voters shrink below 15% of the electorate, legislatures struggle to build consensus on non-partisan issues like infrastructure or debt ceilings. Understanding realignment cycles matters because it distinguishes normal electoral churn from systemic fragmentation—the former self-corrects through competition, while the latter risks governance gridlock that undermines institutional legitimacy itself.