Yesterday morning the plaza in front of New York’s City Hall was crowded with local luminaries, shivering under blankets and bundled in winter clothes. Celebrities and politicians, elders from the city's ethnic communities, clergy and union leaders gathered to celebrate the inauguration of the new mayor, Bill de Blasio. Regular citizens were there too. That in itself was notable. De Blasio’s inauguration was the first open to the general public in recent memory.

De Blasio once described himself as a socialist. As a 26-year-old activist and supporter of the Sandinista revolution, he took part in a solidarity trip to Nicaragua. On his first day as mayor, though, he placed himself squarely in the tradition of New York liberals and social reformers. He invoked Fiorello La Guardia, the mayor who established the city’s social housing in the 1930s and 1940s, and swore his oath on a bible that once belonged to Franklin Roosevelt.

New York is now the unequal city in the United States and, according to some estimates, the gap between rich and poor rivals Namibia's. Nearly half the city’s residents live at or below the poverty line. As the cost of housing has soared, so have the number of homeless: 60,000, including 22,000 children. One of de Blasio's campaign slogans was ‘a tale of two cities’, one for the rich and another for the rest.

In his inaugural address, de Blasio called inequality a ‘crisis’, and compared it to 'fiscal collapse, a crime epidemic, terrorist attacks, and natural disasters'. He laid out a handful of concrete policy proposals, including a new tax (‘about the cost of a small soy latte’) on New Yorkers who make over $500,000 a year that will be used to pay for universal pre-school. His mission, he said, is a ‘march toward a fairer, more just, more progressive place’.

Sitting behind the new mayor on the stage in front of City Hall was the man who worked there until the day before. Michael Bloomberg does not look amused easily, but he had reason to frown on New Year’s morning. In one remark after another, speakers castigated his 12-year reign. (Bloomberg fought to change term limit laws to allow himself a third term.) Opening the ceremony, Reverend Fred Lucas of Brooklyn Community Church described New York as a ‘plantation’ and prayed that the new administration would deliver ‘emancipation’. Other speakers made digs at the former mayor’s policies, such as supporting the building of a massive sports arena when there was a desperate shortage of affordable housing, or introducing stop-and-frisk policing, which a federal court recently ruled illegally targets New York’s black and Latino men. The only New Yorker with anything positive to say about the outgoing mayor was his successor.

(London’s mayor, another quirky ‘moderate’ with a media background, plenty of money and a penchant for ‘pragmatic’ problem solving, might take note. Bloomberg and Boris Johnson are said to be friends and through their overlapping years have held more than a few high-profile summits. And the growth in inequality in London has largely kept pace with New York.)

American liberals are taking heart. But anyone who thinks a new New Deal is coming to America’s cities shouldn't hold their breath. For one thing, de Blasio chose a former Goldman Sachs executive to head his housing initiative. But most important, it's not clear what the new mayor can do to take on one of the biggest drivers of inequality: finance. Wall Street's power and influence is far more than a municipal issue.