If you need data on a single census tract, there are several ways you can acquire it:

• The census bureau provides a census tract locator that gives the census tract and a demographic profile for any address in the country.
• The Federal Financial Institutions Examination Council (FFIEC) (official site) offers a very similar geocoding/mapping service which does the exactly same thing as the census tract locator, but with a slightly more elegant interface.

click here to open the FFIEC's census tract locator in another window

click here to open the census bureau's census tract locator in another window

once you have the number of the census tract(s) in your area, click here to continue