  union township is a township in adams county, pennsylvania, united states. the population was 3,148 at the 2010 census. ==geography== union township is located in the southeast corner of adams county. it is bordered by york county (west manheim township) to the east and by carroll county, maryland, to the south. germany township and the borough of littlestown border union township to the southwest, mount pleasant township is to the northwest, and conewago township is to the northeast. according to the united states census bureau, the 
Populated_places_established_in_1735 Townships_in_Adams_County,_Pennsylvania Townships_in_Pennsylvania