Today the 1940 census was released, opening up the personal details of 132 million people for the first time after 72 years of privacy protection lapses—21 million of those people are still alive. There are a number of ways to access the information in the census, including at the National Archives and this website, and the New York Public Library has also released a search tool.
Kate Stober at the NYPL tells us it's "more than just a research tool, we’ll be helping New Yorkers create a social history map of buildings and neighborhoods in the five boroughs. When you find an address, the tool pins it to both a 1940 map and a contemporary map, so you can see how the area has changed. You’re then invited to leave a note attached to the pin—memories, info about who lived there, what the neighborhood was like, questions... As people use the site, we’ll build a cultural map of New York in 1940 that will assist both professional historians and laypeople alike." And that's pretty amazing.
You can search through it here. We gave it a spin attempting to find Al Pacino and Woody Allen's families, but didn't have any luck (yet)... but lo and behold, America's number one recluse was right there in a plain site. Here's J.D. Salinger's personal deets from the year (13 years prior to living in seclusion in New Hampshire):

Someone also found Stanley Kubrick's father's listing, noting, "Jack Kubrick is the father of the famous director Stanley Kubrick. In 1940, Stanley will turn 12 in the Bronx a couple of years before his father, a doctor, bought him his first camera."