Rusen Cakir, a prominent Turkish commentator, said the elections were as important as those of 1994, when Erdogan first became mayor of Istanbul. "It is is a declaration that a page that was opened 25 years ago is being turned."
The results tell us a couple of things about the state of Turkish politics 15 years after Erdogan came to power and three years after he began an accelerated crackdown in response to a failed coup against him.
The first is that the rules of political gravity still apply in Turkey. The country is in the grip of a recession and voters responded by doing something extremely normal: They punished the party in power.
That might not sound like much to get excited about. But many analysts feared that Turkish democracy had become so distorted that even the most basic public sentiments could no longer find political expression. We now know they can.
Another lesson is that Turkey's opposition is still alive and kicking, even in the face of political persecution by state authorities and a media that is overwhelmingly loyal to Erdogan.
The main opposition, the secular Republican People's Party, still retains a mass membership and the machinery to fight elections. Its survival is a sign that Turkey's democratic roots may be frayed but they are deep.
Compare the situation in Turkey to Egypt, where there is essentially no politics left. The military-led Government in Cairo has stamped out nearly all organised opposition and denied them any space at all within the political process. Turkish politics is vibrant by comparison.
But those predicting that the election results are the beginning of the end of the Erdogan era should pause for breath.
Turkey has no elections scheduled for the next four years, meaning it will be difficult for the opposition to channel its victory into broader political momentum.
The AKP may have lost major city elections but nationwide it still won more votes than any other party. Along with its nationalist allies, it appears to have won more than 50 per cent of the vote, suggesting it can still win a national election.
And while Erdogan may be prepared to accept defeat in local elections, his party is more likely to deploy dirty tricks if control of the presidency or Parliament is at stake. Its defeat this week may only strengthen its resolve to win the next election by any means necessary.
The results in Istanbul and Ankara should be seen for what they are: A hopeful reminder that the battle for Turkish democracy is not yet lost.