Butler County posted a 4.7-percent unemployment rate in April, the lowest rate in a 9-county area of Western Pennsylvania, according to the state Department of Labor and Industry. The other counties bordering Butler County had rates above 5 percent. Butler's rate was ranked 11th lowest in the state. The other rankings were Allegheny, 17; Westmoreland, 23; Mercer, 30; Clarion, 34 (tie); Venango, 34 (tie); Beaver, 41; Armstrong, 49 (tie); and Lawrence, 49 (tie).