"An enumeration district, as used by the Bureau of the Census, was an area that could be covered by a single enumerator (census taker) in one census period. Enumeration districts varied in size from several city blocks in densely populated urban areas to an entire county in sparsely populated rural areas" (1940 Census website from the National Archives)
The National Archives have made 1940 Census records available online through the 1940 Census website. This site is set up for browsing by location. While you can browse by street name, many streets are long and will show you large numbers of results, so in order to find Census schedules for a small area of interest, it is most efficient to find the enumeration district number first.
In order to research your neighborhood of interest:
Note: Some Ancestry functionality is currently limited for off-campus users. Browsing Census schedules by enumeration district is currently available on-campus only.
For 1940 Census schedules only, see also http://1940census.archives.gov/, an open access project of the National Archives.
Ancestry.com is a useful tool for accessing census schedules. Unfortunately for researchers of cities, it was designed primarily for genealogists, and therefore is much easier to search by name of resident rather than location of residence. In order to research your neighborhood of interest:
Year: 1940; Census Place: Baltimore City, Baltimore, Maryland Enumeration District: 4-495