Former Vice President Joe Biden s decisive victory over President Donald Trump makes him the first challenger to defeat an incumbent president in the 21st century and only the fifth in the past 100 years. From those who took to the streets in celebration on Saturday, to signs of relief around the globe, its clear that many people are relishing the defeat of an American president who has frequently exhibited dangerous authoritarian tendencies.

Trump also tapped into the deep divisions long stoked by political partisans and inflamed them more than anyone who came before him. President-elect Biden now pledges to usher in a period of healing and unity . But this years election shows that the unstable politics that produced Trump are not going anywhere.

A 5 million vote lead (and counting) will not produce an easy governing mandate for Biden. Even though his current 50.9% share of the electorate will be higher than any challengers since Franklin Roosevelt, it could have easily gone the other way. A change of less than 50,000 votes across Arizona, Georgia and Wisconsin would have produced an Electoral College tie and delivered Trumps reelection despite his losing the popular vote by more than 5 million votes.

Bidens Democratic Party will also hold one of the slimmest majorities in the still-gerrymandered House of Representatives, after losing seats in the election, and can only hope for a tie in the Senate, if two runoff elections in Georgia go the partys way.

And this year wasnt a one-off. Hillary Clinton famously won the popular vote but lost the Electoral College by a large margin. This is the era were living in. Its one of divided government, competitive elections, ideological polarization, vicious partisan combat and anti-majoritarian obstacles that combine to create escalating crises as the parties but mostly the Republicans seek any advantage to hold and wield power.

The country is still divided in the way it came to be in the wake of the 2000 election between Vice President Al Gore and Texas Gov. George W. Bush. That election produced the first unpopularly elected president since the 19th century, the smallest House majority since before the Civil War and a Senate tied at 50-50. It was also the last presidential election in which 10 or more states voted for a candidate from a different party than they had in the previous election. The 2000 election saw a crescendo in the politics of partisan polarization created by the return of competitive congressional elections in 1978 and the victory of Ronald Reagan in 1980.

The 2000 election even produced a symbolic representation of our divided politics: the red state-blue state map , which entered popular parlance during the long post-election stretch when there was no clear winner. Politicians now reach for the red state-blue state language when they seek to transcend our polarized divisions, as Barack Obama did in his 2004 speech to the Democratic National Convention , or to exploit them for political gain, as Trump does in statements denigrating Blue States that elect Democrats .