Port Harcourt was founded in 1912 by Frederick Lugard, governor of both the Northern Nigeria Protectorate and the Southern Nigeria Protectorate. Its purpose was to export the coal that geologist Albert Ernest Kitson had discovered in Enugu in 1909. The colonial government caused the people of Diobu to cede their land, and in 1912 the building of a port-town was started Other villages that were later absorbed into the city included Oroworukwo, Mkpogua, and Rumuomasi. In the creeks to the south of the original port were the fishing camps and grounds of the Okrika-Ijaw group.
During the First World War, Port Harcourt was used as a point for military operations against the Central Powers in German Kamerun. After the discovery of crude oil in Oloibiri in 1956, Port Harcourt exported the first shipload from Nigeria in 1958. Port Harcourt became the centre of the Nigerian oil economy and it subsequently reaped benefits of its associations with the petroleum industry by undergoing modernisation and urbanisation. Port Harcourt's growth is further due to its position as the commercial centre and foremost industrial city of the former Eastern Region; its position in the Niger Delta; and its importance as the centre of social and economic life in Rivers State. After the Republic of Biafra seceded from Nigeria in 1967 Port Harcourt fell to Nigerian forces on 19 May 1968. From an area of 15.54 km2 in 1914, Port Harcourt grew uncontrolled to an area of 360 km2 in the 1980s.
The main city of Port Harcourt is the Port Harcourt City in the Port Harcourt local government area, consisting of the former European quarters now called Old GRA and New Layout areas. The urban area (Port Harcourt metropolis), on the other hand, is made up of the local government area itself and parts of Obio-Akpor accordingly. Port Harcourt, which is the current capital of Rivers State, is highly congested as it is the only major city of the state
In 2009, a law was passed by the Rivers State House of Assembly and governor Amaechi's administration to spread development to the surrounding communities as part of the effort to decongest the Port Harcourt metropolis. The Greater Port Harcourt region, spans eight local government areas that include Port Harcourt, Okrika, Obio-Akpor, Ikwerre, Oyigbo, Ogu–Bolo, Etche and Eleme. Its total population was estimated at 2,000,000 as of 2009, making it one of the largest metropolitan areas in Nigeria.
Some of Port Harcourt's more popular and well-known residential areas are
The main industrial area is located in Trans Amadi.
Port Harcourt is a major industrial centre as it has a large number of multinational firms as well as other industrial concerns, particularly business related to the petroleum industry. It is the chief oil-refining city in Nigeria and has two main oil refineries that process around 210,000 barrels of crude oil a day, both operated by the Port Harcourt Refining Company.
Rivers State is one of the wealthiest states in Nigeria in terms of gross domestic product and foreign exchange revenue from the oil industry, crude oil being its principal export earner. Microapartment architecture is quite common in certain parts of Port Harcourt. The Point Block of Rivers State Secretariat is an icon of the city. An 18-story building, it is the tallest building in the South East and South South geopolitical zones combined.
Aside from being the oil capital, Port Harcourt is also known for the vibrant late-night activities and entertainment scene. There are several public houses, lounges, clubs, dance bars and restaurants spread out around the city. Partyers and revellers tend to spend a chunk of their night time at New GRAs, where most of the bars and high-end nightclubs are located. Uptempo and club-friendly music can be heard in nearly every corner of the city at night. There have been increases in sex- oriented businesses including strip clubs and brothels. Prostitutes who operate out of these red-light districts mainly fall in the 18-30 age bracket and may charge as high as ₦25,000 a night, if not more.
As of 2016, the Port Harcourt urban area has an estimated population of 1,865,000 inhabitants, up from 1,382,592 as of 2006.
There are a number of institutions of tertiary education in Port Harcourt, mostly government-owned. These institutions include, Rivers State University, University of Port Harcourt, Port Harcourt Polytechnic, Ignatius Ajuru University and Rivers State College of Health Science and Technology.
Port Harcourt's primary airport is known as Port Harcourt International Airport, located on the outskirts of the city.