Four years ago I asked for the 21 potential landing sites for the Mars 2020 mission in this question, but now I've learned that there were more than 60 candidate locations !
From NASA Announces Landing Site for Mars 2020 Rover:
NASA has chosen Jezero Crater as the landing site for its upcoming Mars 2020 rover mission after a five year search, during which every available detail of more than 60 candidate locations on the Red Planet was scrutinized and debated by the mission team and the planetary science community.
Were those over 60 candidate locations recorded and/or described somewhere and can they still be tracked down ?