The area code for Lancaster County Pennsylvania. The 717 is the only way to refer to Lancaster county because it you refer to it as Lancaster, strangers will most likely ask you if you live near amish people.
Bro 1: Yo Brah. Lets get out of this hell hole and get our shit back to the 717.
Bro 2: You mean Lancaster right?
Random stranger: Do you live near amish people?
Bro 1: Fuck you random guy. Thats why we say the 717 instead of Lancaster ass hat