New York City marked the fourth anniversary of superstorm Sandy on Saturday with the mayor’s lament that he didn’t keep his promise to rebuild all single-family homes by year’s end.

Barely half are done.

Last year, on the storm’s third anniversary, Mayor Bill de Blasio pledged that the Build It Back program would be “getting families home” after one of America’s worst storms.

But of the 4,025 city-managed construction projects at issue, about 55 percent have been completed and 77 percent started, according to figures from Matt Viggiano of the Mayor’s Office of Housing Recovery Operations.

De Blasio said Saturday setting the goal “allowed us to move a lot of projects that were stalled” and “provided a way to focus everyone’s energy.”

“Everyone knows we have fallen short of that goal. That disappoints me deeply,” de Blasio said on Staten Island to celebrate the opening of a Sandy-delayed water tunnel.

The figures don’t include the thousands more homeowners who opted for checks instead of city-managed reconstruction.

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In 2014, when de Blasio took over the rebuilding effort from his predecessor, Michael Bloomberg, no homes were under construction and no checks issued.

The project is now $500 million over budget.

“It’s such a surreal feeling: There’s a part of me that feels like this storm happened a few months ago,” Staten Island Borough President Jimmy Oddo, a Republican, said at the Democratic mayor’s side. “And then there’s another part of me that is so fatigued and frustrated by all this. It feels like it’s been much longer than four years.”

The 2012 storm killed 117 people, including at least 43 in the city and 13 on Long Island. The storm damaged or destroyed about 100,000 housing units on the Island and 70,000 in the city.

On Saturday, de Blasio said by year’s end 90 percent of the home construction would be under way and 75 percent completed. He said he’d review what went wrong over the last year that kept the administration from meeting last year’s pledge.

“If I go back and feel that there was something that wasn’t done right that could have been done different,” the mayor said, “then I’ll evaluate whether there needs to be other consequences.”