The New York Public Library (NYPL Research Libraries) offers borrowing privileges, study rooms, and off-site access to e-resources.
MaRLI, the Manhattan Research Libraries Network, allows those approved by NYPL to visit and borrow from Columbia and NYU Libraries.
METRO referrals allow single-day, on-site access to NYC libraries, based on the need for an item that is otherwise unavailable.
SHARES extends university and museum library on-site access to visitors with a current GC photo ID.
GC Interlibrary Loan delivers most resources from other libraries to the GC for pickup.