"New York is far more crowded than any other major city in the United States. It has 28,000 residents per square mile..."

"... while San Francisco, the next most jammed city, has 17,000, according to data from the U.S. Census Bureau. All of those people, in such a small space, appear to have helped the virus spread rapidly through packed subway trains, busy playgrounds and hivelike apartment buildings.... Dr. Deborah L. Birx, the White House’s coronavirus response coordinator, said on Monday that the 'attack rate' — the percentage of the population infected with the virus — was nearly one in 1,000 in the New York area, five times higher than in other parts of the country.... The city now has more coronavirus cases per capita than Italy.... [Governor Andrew Cuomo] said... people had been gathering in parks over the weekend and not staying far enough away from each other. He said he was still awaiting a plan from the city to prevent residents — especially young people — from getting too close, perhaps by imposing more controls on public spaces and opening some streets to pedestrians."

From a NYT article titled "Density Is New York City’s Big ‘Enemy’ in the Coronavirus Fight."

NYC can't change the number of residents per square mile, but it can change density in the sense of distance between people. Here's Cuomo, yesterday, talking about a plan to reduce density (and chewing out the young people who go to the park as if it's a day in the park):