Many online resources are available to help you learn about New York City in the 1940s. Here are some links to help you in your research.
1940 Census
The National Archives and Records Administration (NARA) in partnership with the U.S. Census Bureau has made available online the original record forms prepared by Census enumerators in 1940. Several websites provide access to this information, including:
In New York City, the NY Public Library provides an online service to make it easy to determine the street addresses for your ancestors, which you'll need to search the sites above.
Life in New York City in the '40s
The NYPL 'DirectMeNYC' site has a great FAQ with links to online resources about New York in the '40s, such as:
Other online sites with information about life in New York City in the 1940s include: