Richard Florida does some number crunching to determine which factors correlate with multiple marriage:
Multiple marriage was significantly less likely in states with high immigrant concentrations (-.38). Multiple marriage was also less likely in states with high bohemian concentrations (-.49). So much for the libertine bohemian lifestyle - at least when it comes to multiple marriage that is. There was no correlation between multiple marriage and the share of the gay population.
(Sign from the Equality March)