This Census is noteworthy in that it is the last one where all of the names of all of the respondents (willing and unwilling) are listed. However, you can't look anyone up by their name because there is no index; instead, you may need to use the Enumeration District in which they were counted (probably their place of residence, but if they were traveling, or in prison, or in the hospital, or something of that nature, then it could be different). Thankfully, the Census Bureau has provided us with a tool that makes it not too difficult to do just that. Obviously, if you are searching for someone in a small town, it will be easier to find them than it would if you were looking for someone in a large city.
The cool thing about this is, you probably know someone who was alive in 1940; they may remember the Census-taker knocking on the door and asking all of these questions. You should ask them. And if you are alive and remember taking part in the 1940 Census, send an email and use "1940 Census" as the subject. We'd love to hear about it!
In the meantime, you are welcome to visit at Library Headquarters to check out the census rolls we have on microfilm. You never know what you might find!
Image, The Great Plastic Dino Census, courtesy denn.