OH MY GOD EVERYBODY I just learned about reciprocard.com , which lets you enter your public library and find out all the places you can get a card on Libby. I had not known my Minuteman card actually gave me *every network in the state*, including the flawlessly-named CLAMS?!?!
ReciproCard - Reciprocal Library Cards for LibbyDiscover which reciprocal library systems you can access based on where you live. More cards means more books on Libby.reciprocard.com