That it took so long for Ms. Heras to find an affordable home says much about the state of housing in New York. That she found it in the Bronx, once a symbol of urban blight, says something locals have known for years: The Boogie Down is on the rise. Now the rest of the city is catching on.

The borough has come a long way since 1931, when Ogden Nash wrote the derisive couplet “The Bronx? No Thonx.” From Riverdale in the north to Mott Haven in the South, the Bronx is bursting with new development, much of it geared toward affordable housing — or some semblance of it.

A $165 million deal that closed last week in the South Bronx, perhaps the borough’s largest private development, could bring about 1,300 new rentals to the industrial waterfront, of which 30 percent will be affordable. The recent rezoning of more than 90 blocks along Jerome Avenue, which cuts through the poorest congressional district in the country, could bring 4,000 new low- and middle-income apartments.

New infrastructure, including four proposed Metro-North Railroad stops, and the recent introduction of a new ferry line, is expected to spur building. And a new federal provision, buried in last year’s tax overhaul, could incentivize even more housing in impoverished neighborhoods by offering tax benefits to investors.

But a popular refrain from critics persists: “Affordable for whom?”

The Bronx remains the poorest borough in the city, with a median household income of $37,525, compared to Manhattan, the richest borough, where the median is $77,559, according to a census analysis by Social Explorer, a research firm. Critics argue that many ostensibly affordable units will still price out locals, whose per capita income is under $20,000, and that new luxury buildings will raise rents further. But even as gentrification looms, the borough offers some of the last remaining bargains in the city, for locals and newcomers alike.