Portland

In Grand Theft Auto III, Portland consists of an island at the eastern end of city limits.

Based on the industrial area of New York City, Portland mostly resembles the run-down areas of Brooklyn that are located directly outside of Manhattan. While Portland Island is known as a primarily industrial portion of the city, focused on varied industries and shipping, a sizable residential and commercial population does reside in the island, as the majority of the island is occupied by several non-industrial districts. Much of the island's industrial population is concentrated towards Trenton at the south of the island, and is within a short driving distance to Portland Harbor and Atlantic Quays, which serves as seaports to the island and the city. Non-industrial properties tend to reside towards the north and west sides of the island. Portland also operates an elevated train service with three stations (Rothwell Station in Hepburn Heights, Kurowksi Station in Chinatown, and Baille Station in Saint Mark's) that runs within the island.

Chinatown, located northwest from the industrial districts, houses a Chinese-American population, with Chinese-owned commercial, industrial and residential property evident in the district; some of these properties are also believed to be controlled by the local Triads. The Saint Mark's district, located on a steep terrain north from Portland Harbor, is home to an Italian-American population, and is currently controlled by at least two Mafia families: the Leones and the Forellis. As the Triads and Mafia are enemies to each other, skirmishes between members from the Triad and the Mafia occur frequently in areas bordering Chinatown and Saint Mark's.

Other districts of interest include the Red Light District, just west of Saint Mark's, which serves as a prime location for strip clubs and pornography-related businesses. Hepburn Heights, located north to the Red Light District, is home to several apartment projects, and is also home to the Hispanic Diablos street gang. Harwood, located on the northern end of the island, is mostly underdeveloped, with only a few buildings (including the Head Radio broadcast station), a junkyard, and the Porter Tunnel's Portland entrance/exit.

The remaining districts of Portland Island are sparsely inhabited: Callahan Point (also known as Waterfront Promenade) is located under and around the foot of the Callahan Bridge, which links Portland Island and Staunton Island; Portland Beach is an empty cliff-side beach located east of Saint's Mark; while Portland View consists of a tract of land and a stretch of road between Portland Harbor and Chinatown. Old platforms and train cars of a railway line are also found in eastern Harwood, as well as a tunnel running under the Saint Mark's district, which directly links Harwood with Portland Harbor. Portland Rock, a small island housing a lighthouse, may also be seen east of Portland Beach.

The "Portland Beach" area was created to look like the beachy areas in and around New York: Coney Island in Brooklyn, Sandy Hook and Fire Island, which are near the shores of Staten Island and Long Island, respectively. "Chinatown", obviously enough, takes its inspiration from the Manhattan neighborhood of the same name, the "Saint Marks" district takes it name from Little Italy in Manhattan, while "Trenton" takes its inspiration from New Jersey's capital city And The "Red Light District" resembles Manhattan's 42nd Street of the 1980s.