Rockstar always invents place names. Vice City is fictional but Miami-coded; Leonida is fictional but Florida-coded. This page is a working index of which fictional names appear in official material and what they plausibly correspond to in the real world.
Hedged carefully. Several names that appear in community discussion have not been confirmed in any official material; we don't repeat them as fact.
Confirmed in official material
Leonida (state). Vice City (largest urban centre). These are the names Rockstar has used in Newswire posts and trailer text.
Other named locations - if any have appeared on-screen or in official posts at the time you're reading this - we update here. As of this draft, the confirmed-name list is short.
Names from community discussion
Port Gellhorn, Ambrosia, Grass Rivers, Mount Kalaga - these names appear in community trailer breakdowns and freeze-frame work. They may be on-screen; some have been clearly seen in trailer text. Each should be verified against the source before being treated as confirmed.
Where a name appears verifiably in trailer text, we treat it as confirmed. Where it has been propagated through community channels without a clear source, we hedge.
Plausible real-world correspondences
Vice City → Miami. The Keys analogue → Florida Keys. The wetland region → Everglades / Big Cypress. Inland small towns → various central Florida towns.
Specific town-to-town mappings should be treated as inspiration, not as 1:1 correspondence.