The Fourth Republic (1999–present)

The Fourth Republic is Nigeria's present system of government, in place since 29 May 1999, when the constitution of that year came into force and Olusegun Obasanjo was sworn in as president (Wikipedia). It followed the transition organised by General Abdulsalami Abubakar after the death of General Sani Abacha in 1998. Like the Second Republic's constitution, the 1999 constitution sets up a presidential system closer to that of the United States than to the Westminster model, with a National Assembly of two houses: a 109-member Senate and a 360-member House of Representatives.

Wikipedia lists the presidents of the Fourth Republic. Obasanjo of the People's Democratic Party (PDP) served two terms, from 1999 to 2007. Umaru Musa Yar'Adua of the PDP won the election of April 2007, which international observers strongly criticised. Yar'Adua died on 5 May 2010, and the vice-president, Goodluck Jonathan, became president; Jonathan won the 2011 election, regarded as freer and fairer than earlier ones. In the election of 28 March 2015 Muhammadu Buhari of the All Progressives Congress (APC) defeated Jonathan, ending sixteen years of PDP rule; Buhari, sworn in on 29 May 2015, was the first opposition candidate to win a presidential election since independence. He was re-elected in 2019. Bola Tinubu of the APC won the presidential election of February 2023, which the opposition accused of fraud, and was sworn in on 29 May 2023.

Wikipedia's history of Nigeria records some of its major challenges: communal violence, conflict in the oil-producing Niger Delta, a dispute with Cameroon over the Bakassi Peninsula, and the insurgency of Boko Haram, which in 2014 kidnapped some 200 schoolgirls at Chibok. It also records large infrastructure projects, such as the Lagos–Ibadan standard-gauge railway (operating from 2021) and the Second Niger Bridge (completed in 2022).

This period is current: its account will be extended as events happen.