The folks at ancestry.com are very clever-their free thanksgiving pass got be hooked into another subscription-something which I swore never to do again (I found them sleazy). I see though that they have made their rates come down to earth. Knowing Betty's real name (Elisabeth Wehner), my census search discovered she lived in 1900 at: 702 Grand Street, in 1910 at: 227 Skagg. In 1920 she could not be found in NYC, but I found her mother remarried to Michael Keogh ( a policeman just like in the book) living in a private home at 115 Schaefer Street (Bushwick). Her mother later moved to Queens and died at age 91.
There is an extensive online biography, written in 2003, of Betty Smith (the lady's problems didn't end with childhood) by Dr. Carol Siri Johnson. My hunch that Smith might have attended PS 18 could be true since that school is the closest to the Grand Street and Skagg Street addresses. Alas, though, it seems my attempt to woo the current principal of the school to do a "Tree Grows In Brooklyn" project has failed. Here's what some High School kids did with an honors English project centering around the book. It's not bad, but can you imagine what some local Williamsburgh kids could do. I also think it can be done with 5th graders if the book is presented as a read aloud with the help of the audio version and the film.