Hanover is a borough in York County, Pennsylvania, 19 mi southwest of York and 54 mi north-northwest of Baltimore, Maryland and is 5 mi north of the Mason-Dixon line. The town is situated in a productive agricultural region. The population was 15,289 at the 2010 census. The borough is served by the 717 area code and the ZIP Codes of 17331-34. Hanover is named after the German city of Hannover.