When Bill de Blasio declared in his inauguration speech he’d “take dead aim at the Tale of Two Cities,” he left no doubt what he meant.

“We will require big developers to build more affordable housing,” the new mayor said.

So far, after five years in office, de Blasio claims to be well on the way to “creating or preserving” 300,000 affordable housing units by 2026. But the reality tells a different story.

Among the 300,000 total, 180,000 are in the “preserved” category. Usually this means that landlords agree to keep some apartments rent-regulated in exchange for tax breaks. De Blasio’s largest “success” is at Stuyvesant Town, where the landlord will keep 5,000 units rent-regulated for 20 years in exchange for $220 million in taxpayer subsidies.

But the Independent Budget Office later found that the numbers were wildly misleading, because 1,800 of the 5,000 units would have remained under regulations anyway.

Apartment “creation” sounds like City Hall built them. In fact the city has neither the land, the resources, nor the legal authority to build more public-housing units than already exist. Deputy Mayor for housing and development Alicia Glen made this clear to The New York Times in October when she said, “When all these advocates run around and say, ‘Why isn’t the City of New York building housing?’ It doesn’t exist. There’s no such thing.”

The few apartments de Blasio can truly claim to “create” are hard to quantify. They include, for example, 293 new units at Camba Gardens II on the Kings County Hospital campus, which opened in April. But the $100 million project was financed with a potpourri of public and private funds — of which the largest portion was $49.3 million in tax-exempt bonds issued not by the city, but by the state. The city’s Housing Preservation and Development agency’s contribution was only $20.5 million.

The total 120,000 “created” is mostly based on wildly optimistic projections in rezoned areas. A “mandatory inclusionary housing” rule requires developers to include a certain number of below-market units in new projects that are either in a rezoned area where larger buildings are newly allowed, or in buildings elsewhere that get a site-specific zoning change to be as large or tall as a developer wants.

But, again, quantifiable results at a handful of locations where de Blasio has taken credit are few and murky. A certain number of cheaper units may pop up in East Harlem, East New York and Far Rockaway — all newly rezoned by de Blasio — but the results are years away.

He crowed over the opening of the Frances Goldin Senior Apartments at the new Essex Crossing complex on Delancey Street last January, where all 99 units are affordable. But nearly all of Essex Crossing’s elements, including the Goldin building, were set in motion under his predecessor Michael Bloomberg. De Blasio did kick in some financing for Goldin, but Bloomberg would have done the same.

Or take the Domino Sugar site in Williamsburg, where developer Two Trees needed a zoning variance to put up 55-story towers as part of a $3 billion office, apartment and public-park complex, rather than 35-story ones previously permitted.

The project, including affordable apartments, was mostly planned under Bloomberg. But de Blasio held it up to include a few more affordables. The mayor’s amen crowd cheered, but over what?

The problem is he promised phony “solutions” that barely make a difference

The original plan called for 660 affordable units of a total 2,300 apartments. De Blasio muscled developer Two Trees to agree to 700. For the “victory” of adding a mere 40 more affordable units, City Hall green-lighted the whole Domino project.

The city as a whole will benefit from Domino’s reclamation of a once desolate waterfront. But most of its apartments will be market-rate. Two-bedrooms in the first completed building are asking over $5,000 a month. The complex is exactly the kind of gentrification-symbolizing enterprise “for the rich” that the mayor supposedly disdains. Yet had he nixed it altogether, he couldn’t claim to have “created” additional affordable apartments.

Ironically, as a result of all the rezonings he’s pushed through to allow taller and larger new buildings, the mayor has accelerated the gentrification of lower-income neighborhoods.

Rezoning to encourage development always raises values and prices — whether in poor East New York, where builders will soon tear down gas stations for new apartments, or rich East Midtown, where Kushner Companies is trying to buy out the co-op owners of an entire Park Avenue building so they can put up a structure up to four times larger.

It’s why residents near Brooklyn’s Broadway Junction subway/elevated station are howling over de Blasio’s proposal to rezone their mostly low-rise, largely impoverished neighborhood. They know that new buildings superior to century-old tenements will draw new investment that will inevitably alter the local chemistry.

Barely one year after de Blasio rezoned East New York, where the city committed $267 million infrastructure improvements to support new development, local organizations complained that the rezoning had already caused rents to rise along subway lines. Meanwhile, there was “minimal affordable housing development, predatory land grabs and tenant harassment,” Gotham Gazette reported.

Meanwhile, every month brings dire news about the city’s housing crisis, particularly the worsening scarcity of affordable homes. In the past few weeks, The Post revealed that unscrupulous property-flippers snatched up and sidelined 15,000 houses and apartments in the past five years, especially in Queens. Demand is so frantic that, as the Times reported last fall, a lottery for one building at Essex Crossing drew 93,000 applications for 104 affordable apartments.

It’s true there isn’t much de Blasio can do to fix the affordable-housing crisis. Global wealth has driven up prices of everything beyond his control. The problem is he promised phony “solutions” that barely make a difference — and pursues policies that have only made the situation worse.

Rather than narrow the gap between the “two cities,” he’s driven them further apart.