You’re conflating two different things.

Jacob Riis inspired basic rules around safety and crowding in apartments and light/air.

Zoning in the US absolutely started as a way to keep poor and black people out of certain areas.

> Zoning determines what can be built where, and is ubiquitous in the United States. Low-density residential zoning predominates in US cities far more than in other countries, limiting housing opportunities for those who cannot afford large homes. These zoning regulations have racist and classist origins, make housing more expensive, and reinforce segregation patterns.

https://www.annualreviews.org/doi/abs/10.1146/annurev-soc-030420-122027

And NYC’s first zoning law was not inspired by Riis. It was inspired by the massive Equitable Building which was just a giant cube that blocked light on the street below. The first zoning law was primarily focused on requiring setbacks.

https://en.wikipedia.org/wiki/1916_Zoning_Resolution

First I didn't write the quote above - that was from OP.

I don't know why/when NYC zoning laws were written, but I do know that today they make residential construction much more difficult than it should be in a city with an extreme housing crisis, especially large apartment/condominium buildings that can actually add substantial housing stock.

Don't think anybody's arguing that residential zones should be opened up for factories. Also NYC doesn't have industrial revolution-like factories anymore - barely anywhere in the US does and it's ludicrous to suggest that manufacturing would take hold in Manhattan again with the cost of labor and land here. Most no longer exist in North America anymore lol.

Rich people abusing zoning is extremely common, probably the main reason these laws continue to exist, certainly not a rare byproduct. So many affluent blocks with single-family homes or townhouses should have multi-story developments.

People with money and government connections manipulate old laws and file frivolous lawsuits to protect an aesthetic that they like and artificially maintain low-density areas in a growing city with a massive shortage of housing and very limited land. Poorer neighborhoods meanwhile get almost all of the affordable/subsidized housing and other NIMBY but necessary things like homeless shelters, addiction treatment centers, massive parking facilities, industrial storage, etc. The result is racist even if the laws were well-intentioned.

I think comments like yours are just as dangerous. You raise unrealistic fears about "overcrowding, pollution, and squalor" which are often (not saying you intended this, but it's a fact) dog whistles for anti-immigrant sentiment, anti-Semitism/racism, homelessness, and addiction. You pretentiously mention an artist who died in 1914 as a way to justify fear of changes in neighborhood density while virtue signaling to avoid the guilt that people would otherwise bear knowing that they are contributing to financial stress, poverty, and homelessness.

Also cities burning down? Seriously? Large parts of modern cities don't spontaneously burn down any more unless there's a direct cause like a massive forest fire or arson on a mass scale during a riot.

Yeah…but if you haven’t heard, wealth isn’t exactly evenly distributed among racial groups in the USA.