I searched the 1940 Census for my great grandfather. I knew the enumeration district the family was in during the 1930 census. Using this information I was able to page through the scanned images and I found him. The link is here: http://1940census.archives.gov/search/?search.result_type=image&search.state=CA&search.county=Alameda+County&search.city=Oakland&search.street=20th+Av&search.cross_street=Foothill+Blvd#filename=m-t0627-00436-00877.tif&name=61-202&type=image&state=CA&index=16&pages=37&bm_all_text=Bookmark
It is interesting because it looks like his 14 year old son was the respondent. I was extra lucky because my great grandfather was one of the few who were asked supplementary questions.
I am very excited by this find and will need to take some time to parse the document.