branchedout, you dont mention which parish you or your parents live but almost all parishes have reciprocal agreements with neighboring ones.
The East Baton Rouge Parish library has a large ebook selection (over 4000) ... more than Philadelphia's and offer non-residents a card but dont state which parishes so you may need to call.
Also, I noticed Shreveport has a modest (1500 with half fiction) ebook selection and participates in their GreenGold system.
It appears the northeast part of Louisiana has no offerings as far as I can tell. Again the reciprocal and non-resident option may be available.
Also, Calcasieu Parish has about 1200 fiction ebooks and part of the Southwest library system.