Diffusion of social values through the lens of US newspapers

Changing attitudes are the result of a battle for hearts and minds in which agents for and against change try to persuade others. We know very little about this process. This paper develops a methodology for measuring sentiments for and against an idea in the media which we apply to attitudes to gay rights. We uncover several stylized facts: First, the expression of both pro- and anti-gay sentiments in U.S. newspapers follow an S-shaped pattern, characteristic of diffusion processes. Anti-gay sentiment starts its diffusion process later but it catches up with pro-gay sentiments. Second, in the year gay marriages are introduced we observe a dramatic increase in coverage of both pro- and anti-gay sentiment; the increase in the latter is larger. The rise in coverage is still present in the three years subsequent to the institutional change. Third, we document the existence of substantial spatial autocorrelation in media coverage of sentiment