The authors agree that this surname derives from the Latin term porta ("passage", "entrance to the city") and originally designated those who lived near the gate of a walled town or city, or else were its keepers. S. Vannozzi specifies that this is a byname arisen from a common place-noun proper to the medieval period, and notes that the etymology goes back to the Late Latin porta, portae, with a connection to the Greek root por or per ("passage"), in relation to the Greek peráo ("I pass through").

F. Miranda adds that the surname may also derive from one of the numerous Italian place names called Porta. Vannozzi documents its presence in Cercemaggiore, in the province of Campobasso, in Molise, from the end of the 18th century.

As for its distribution, E. Rossoni and Miranda agree that La Porta is very widespread in southern Italy, especially in Sicily, Calabria, Campania, Apulia and Molise. Rossoni further notes that the variant Laporta, less widespread, has a pocket in the Trieste area and is well established in Apulia. Miranda adds a presence in Lombardy, Piedmont, Lazio, Tuscany, Emilia-Romagna and Abruzzo, and stresses that in Sicily the surname appears in every province, with a particular concentration in Agrigento, Palermo, Catania and Trapani.