For many urban dwellers, the country conjures up images of clean air, fresh food and physical activities. But these days, Americans residing in major cities live longer, healthier lives overall than their country cousins -- a reversal from decades past. Many cities that were once notorious for pollution, crime, crowding and infectious diseases have generally cleaned up, calmed down and spread out in recent years, while rural problems have festered. Rural residents are now more likely than other Americans to be obese, sedentary and smoke cigarettes. They also face higher rates of related health problems including diabetes, stroke, heart attacks and high blood pressure, according to County Health Rankings, a research project that recently issued its second annual report of state-by-state comparisons of health measures in every U.S. county.