Workers in hazmat outfits were seen stacking wooden coffins in deep trenches in Hart Island.
Officials say burials are being ramped up at site, which has long been used for people with no next-of-kin or families who cannot afford a funeral.
New York state now has more coronavirus cases than any single country.
The state’s confirmed caseload of Covid-19 jumped by
10,000 on Thursday to 159,937, of whom 7,000 have died.
Spain has recorded 153,000 cases and Italy 143,000, while China, where the virus emerged last year, has reported 82,000 cases.
The US as a whole has recorded 462,000 cases and nearly 16,500 deaths. Globally there are 1.6 million cases and 95,000 deaths.
The drone footage comes from Hart Island, off the Bronx in Long Island Sound, which has been used for more than 150 years by city officials as a mass burial site for those with no next-of-kin, or families who cannot afford funerals.
Normally, about 25 bodies a week are interred on the island, according to the Associated Press news agency.
But burial operations have increased from one day a week to five days a week, with around 24 burials each day, said Department of Correction spokesman Jason Kersten.
Prisoners from Rikers Island, the city’s main jail complex, usually do the job, but the rising workload has recently been taken over by contractors.
It is not clear how many of the dead have no next-of-kin or could not afford a funeral. However, the city has cut the amount of time it will hold unclaimed remains amid pressure on morgue space.
New York City Mayor Bill de Blasio indicated earlier this week that “temporary burials” might be necessary until the crisis had passed. “Obviously the place we have used historically is Hart Island,” he said.
The number of coronavirus deaths in New York state increased by 799 on Wednesday, a record high for a third day. But Governor Andrew Cuomo took heart from the fact that the number of Covid-19 patients admitted to New York hospitals had dropped for a second day, to 200.
He said it was a sign social distancing was working. He called the outbreak a “silent explosion that ripples through society with the same randomness, the same evil that we saw on 9/11”.
Another glimmer of hope was heralded on Thursday as official projections for the nationwide death toll were lowered.
Dr Anthony Fauci, a key member of the White House’s coronavirus task force, told NBC News’ Today show on Thursday the final number of Americans who would die from Covid-19 in the outbreak “looks more like 60,000”.
In late March, Dr Fauci estimated “between 100,000 and 200,000” could die.
The 60,000 projection would match the upper estimate for total flu deaths in the US between October 2019 to March 2020, according to government data.
But Vice-President Mike Pence stressed on Thursday that Covid-19 was about three times as contagious as influenza.
The White House has previously touted estimates that 2.2 million Americans could die from coronavirus if nothing was done to stop its spread.
Stay-at-home orders have in the meantime closed non-essential businesses in 42 states, while drastically slowing the US economy.
New data on Thursday showed unemployment claims had topped 6 million for the second week in a row, bringing the number of Americans out of work over the last three weeks to 16.8 million.
Chicago, meanwhile, imposed a curfew on alcohol sales from 21:00 local time on Thursday to stop the persistent violation of a ban on large gatherings.
The measure, due to remain in place until 30 April, comes after health officials this week said black Chicagoans account for half of all the Illinois city’s coronavirus cases and more than 70% of its deaths, despite making up just 30% of the population.
Figures from Louisiana, Mississippi, Michigan, Wisconsin and New York reflect the same racial disparity in coronavirus infections.
Presumptive Democratic White House nominee Joe Biden joined growing calls on Thursday for the release of comprehensive racial data on the pandemic.
He said it had cast a spotlight on inequity and the impact of “structural racism”.
