When the Second Vote Decides analyzes a wealth of information in the course of examining the impact of elections in which a plurality vote does not determine the winner. The types of elections include traditional runoffs (as practiced in much of the South and many municipalities across the country), the instant runoff (also known as ranked choice voting and the alternative vote), and Top Two elections (as used in California and Washington). The datasets used include one from the traditional states that spans from 1970 to 2019; Top Two results from the time of their adoption in California and Washington through 2019; county-level results from Georgia from 1954 to 1994; results from North Carolina during the period when the state had 40% as the threshold for nominations; and ranked choice voting for municipalities and states (Alaska and Maine), beginning with the adoption of the format in San Francisco through 2022.The book explores the many impacts that a runoff system has on elections, assessing the differences between Democrats and Republicans and general election versus primary runoffs. The author draws on numerous datasets, supported by interviews with candidates and political consultants, to explore the frequency with which the initial leader wins the second round, the impact on incumbents seeking re-election, and whether requiring a majority vote disadvantages women or minority candidates. Some questions explored in the volume include: how does the messaging of the candidates change in a runoff? What happens in a runoff in terms of staffing, targeting, fund raising, and endorsements? How do runoffs, ranked choice voting, and plurality elections compare, and which approach is most desirable?