Alright, here you go. Are you ready? I shall say to Elendil’s Heir: What are you, the fucking hummingbird?
Take it away! 
No, thanks.
My friend Dan in Brooklyn passed this along to me - there was a working farm in Manhattan even in the early 1930s: The Last Working Farm – | My Inwood
Seneca Village: Seneca Village - Wikipedia
In detail: Seneca Village and Little Africa: Two African American Communities in Antebellum New York City on JSTOR
I am happy to say I am a neighbor and friend of one of the principal investigators of the site.
For what it is worth, my father use to take the train from an immigrant area of Manhattan* to the Bronx to get out to the country. He also use to swim in the East River which sounded inconceivable when I was a kid. But Manhattan was pretty close to built up by the 1930s.
- I think east side, probably close to where the UN is today. Think tenements.
This question reminded me of Jack Finney’s time travel novel “Time and Again” which has some very good descriptions of life there in 1882, when it was not built up.