Democratic mayors are in charge of almost all of the United States' 10 most dangerous cities, based on analyses of the latest available national data on violent crimes and the cost of crime.NeighborhoodScout and MoneyGeek used different methodologies to gauge the most violent and costliest crime cities, although five of the cities ended up on both lists.NeighborhoodScout’s report is based on the number of violent crimes per 1,000 residents in cities with 25,000 or more people. The data are based on the number of violent crimes reported to the FBI in each city, projections of violent crime rates based on...