[Jesse R.] Harrington and [Michele J.] Gelfand measure a state's tightness or looseness based on indicators such as the legality of corporal punishment in schools, the general severity of legal sentences, access to alcohol and availability of civil unions, level of religiosity, and the percent of the population that is foreign. But really, that's just the beginning of their analysis. After identifying which states are "tighter" and which are more "loose," the researchers then trace these different outlooks to a range of ecological or historical factors in the states' pasts (and in many cases, lingering into their presents). For as the authors write, tighter societies generally have had to deal with "a greater number of ecological and historical threats, including fewer natural resources, more natural disasters, a greater incidence of territorial threat, higher population density, and greater pathogen prevalence."
That applies nicely to the United States. The "tight" states, it turns out, have higher death rates from heat, storms, floods, and lightning. (Not to mention tornadoes.) They also have higher rates of death from influenza and pneumonia, and higher rates of HIV and a number of other diseases. They have higher child and infant mortality. And then there's external threat: the South, in the Civil War, was defending its own terrain and its own way of life. Indeed, the researchers show a very strong correlation between the percentage of slave owning families that a state had in the year 1860, and its "tightness" measurement today.