The Diffusion of Same-sex Marriage in the United States: An Empirical Assessment of Explanatory Factors and Differing Methods

Open Access
Gest, Caitlin Masterson
Area of Honors:
Political Science
Bachelor of Arts
Document Type:
Thesis Supervisors:
  • David Lynn Lowery, Thesis Supervisor
  • Gretchen Casper, Honors Advisor
  • LGBT rights
  • Same-sex marriage
  • Policy diffusion
  • United States
  • State-level policy
  • State legislature
  • Judiciary
This thesis examines why certain states legalize same-sex marriage at certain times, while others do not, and of those states that do legalize, why some do so utilizing one particular method (the state legislature, the judiciary, or a ballot measure) versus another. A two-tiered event history analysis model is employed to study all fifty American states from 2000 through 2014. The first tier of analysis utilizes a binomial logistic regression to determine the relationships between a number of in-state demographic and political factors and the likelihood of a state legalizing same-sex marriage in a particular year. The second tier of analysis contains only those states that have legalized, and utilizes a multinomial logistic regression to determine the relationships between those same demographic and political factors and the likelihood that a state legalizes in a particular year utilizing a specific method. This paper adopts the hypotheses that certain demographic and political factors impact both the likelihood of a state legalizing, and the method it employs to do so. It also posits that these factors will have differing impacts in the different tiers of analysis, but that political factors will be more significant overall. The results support the idea that there are certain in-state characteristics that impact both tiers, and that they do so in different ways, but do not support the hypothesis that political factors will have a more noticeable overall impact.