What is area code 878?

Area code 878 is an overlay area code for the 412 and 724 area codes in Pennsylvania, United States. It was created in 2013 to provide additional numbering options in those regions when the available phone numbers were running out. Area code 878 serves areas such as Pittsburgh, Greensburg, and Washington. Calls within the overlay complex are dialed with all 10 digits (area code + local number), even if the call is local. The implementation of area code 878 allowed existing phone numbers to remain unchanged while new numbers in the region are assigned with the new area code.