Supporters of the Save Lincolnshire Libraries campaign will march through Lincoln city centre today.
Lincolnshire County Council is proposing to hand over control of 32 of its 47 library services to community groups under moves to save £2 million.
Libraries under threat include many around the city plus rural libraries:
Alford, Birchwood, Boultham, Bracebridge, Bracebridge Heath, Branston, Burgh le Marsh, Cherry Willingham, Coningsby, Crowland, Deepings, Donington, Ermine, Holbeach, Keelby, Kirton (Boston), Metheringham, Nettleham, North Hykeham, Pinchbeck, Ruskington, Scotter, Skellingthorpe, Spilsby, Sutton on sea, Wainfleet All Saints, Washingborough, Welton, Wragby and Caistor.
20,000 people have signed a petition to save the libraries.
The consultation period on the future of the libraries ends on September 30.