"So large are the regional gaps that the poorest set of counties in predominantly blue Yankee Northeast actually have higher life expectancies than the wealthiest ones in the Deep South. At a population level, a difference of five years is like the gap separating the U.S. from decidedly unwealthy Mongolia, Belarus or Libya, and six years gets you to impoverished El Salvador and Egypt.
[...]
Other researchers have found the mortality advantage is greatest among Mexicans in communities where they are more insulated from less healthy U.S. dietary and lifestyle choices than those of Mexican descent who have been in the U.S. for decades or centuries.
Regional differences persist in other measures of health outcomes that contribute to mortality."