The changes have also brought thousands of Hispanics, some legal immigrants and others not, who have migrated up Interstate 270 to meet the demand for construction and service jobs. Until now, the county has handled the influx with outreach classes in schools and community policing programs. Chic Hispanic restaurants flourish in downtown Frederick, and working-class Latinos have remained relatively invisible. Suddenly, however, their presence is igniting a controversy that some fear could escalate into the kind of war over illegal immigration that has torn apart Prince William County. In the past month, the Frederick County sheriff has joined with federal...