Slatedale is an census-designated place in Washington Township, northern Lehigh County, Pennsylvania. It is 3.1 miles west of the borough of Slatington.The village of Slatedale is served by the Citizen's Fire Co #1, Slatedale for fire protection and Northern Valley EMS for ambulance services. While it has its own box post office with the zip code of 18079, surrounding areas use the Slatington zip code of 18080. Both Slatedale and Slatington are named after the large amount of slate found in the area. As of the 2010 census the population was 455 residents.