If you live in Susquehanna County, your library card should have a navy-blue ACCESS-PA sticker on it. You can show your Susquehanna County card at any participating Pennsylvania public library in order to apply for a card there (each library uses its own card, so the one you have is not a "master" card, but it does entitle you to get a card at any participating public library). Each Pennsylvania resident is only supposed to have one ACCESS-PA sticker, on the library card from their home county.

The ACCESS-PA system is also what allows you to return your library items at any other participating public library, and to ask the librarian to request items from other libraries for you.