While Nigeria woke to a new president-elect Wednesday, people said the real winner is democracy, as the country embarks on its first peaceful handover of power since the end of military rule in 1999.
Nigerian President-elect Muhammadu Buhari said his country has "embraced democracy" and put its one-party-state past behind it.
“We have proven to the world that we are a people who have embraced democracy and a people who seek a government by, for and of the people," Buhari said.
He spoke Wednesday in Abuja, just hours after the electoral commission declared him the official winner of Saturday's presidential election, defeating incumbent Goodluck Jonathan by more than 2 million votes.
Buhari says his government will "spare no effort" to defeat insurgent group Boko Haram.
Buhari called Jonathan "a worthy opponent" and said he extends the "hand of fellowship" to the outgoing president.
Jonathan, who conceded, called for peace, saying, “The unity, stability and progress of our dear country is more important than anything else.”
Foreign leaders are praising the two leaders and Nigerians in general for holding a peaceful vote.
In a statement Wednesday, U.S. President Barack Obama congratulated Buhari and said Jonathan "has placed his country's interests first by conceding the election." He placed calls to both men and urged them to work together to unify the country.
Obama said the U.S. would continue to support Nigeria as it confronts challenges, including the threat posed by Boko Haram.
The chairperson of the African Union commission, Nkosazana Dlamini Zuma, said, "The outcome of the elections clearly demonstrates the maturity of democracy, not only in Nigeria but on the continent as a whole."
The election is being praised at the most free and transparent vote yet in Nigeria, despite logistical delays and technical issues at the polls.
There have been no reports of post-election violence in Nigeria - a major change from 2011, when news of Jonathan's victory over Buhari sparked violence in the north that killed about 800 people.
Jonathan's People's Democratic Party has ruled Nigeria since 1999.
Buhari, 72, of the All Progressives Congress, is to be inaugurated May 29.
Nigeria's Electoral Commission chairman Attahiru Jega announced earlier Wednesday that Buhari had officially won the election, getting 15.4 million votes to Jonathan's 12.9 million.
Late Tuesday, when the outcome of the election was apparent, Jonathan conceded defeat and thanked all Nigerians for the opportunity to lead them.
The outgoing president said he kept his promise for a free and fair election. He appealed to anyone who does not like the outcome to follow due process under the constitution and election laws. Jonathan said nobody's ambition is worth the blood of any Nigerian.
President-elect Buhari was previously Nigeria's military ruler for 20 months after officers seized power in a December 1983 coup.
He was toppled by another military coup, but has run for the presidency four times since democracy was restored in Nigeria in 1999.
In Kano, the largest city in the north, people partied into the night, cheering as drivers spun their cars through a roundabout.
There was giddiness and a sense of empowerment in the streets. People danced. They jumped up and down. In Abuja, they chanted and sang “Father, father” in Hausa. But they also said they want results, and they will let Buhari know how he is doing in four years at the next election.
In Abuja, APC supporters started gathering at party headquarters Tuesday, waiting for Buhari as results were being announced.
“He will turn the country around. We know that But it is going to take time because the country is in a state of complete decay. So we are not under any illusion that there is a miracle going to happen straightaway," Hadja Lamisila said.
On Wednesday, U.N. High Commissioner for Human Rights Zeid Ra’ad al-Hussein said the appalling atrocities committed by Boko Haram have created a human rights crisis resulting in at least 15,000 deaths since 2009 in northern Nigeria and the Lake Chad region.
As Buhari takes office, the Boko Haram insurgency rages in the northeast.
It intensified dramatically on Jonathan’s watch: thousands of civilians have been killed, more than a million displaced. Borno state, which has been most affected by the Islamist insurgency, was the last state to file election results.
The entire election was postponed for more than a month because of fighting and instability in the northeast, where Boko Haram has been battling the government since 2009.
Nigerians also voted for members of parliament.
Overall, observer missions from the African Union and the Economic Community of West African States said despite logistical problems and some violence, the organization of the election was "acceptable."
The election was supposed to have been held for just one day, Saturday. But voting was extended into Sunday because of technical problems.
Chris Stein contributed to this report from Kano, Nigeria.