As of June 8, 2012 several organizations have worked solid since April 2nd to get indexed the states in the recently released 1940 US Census. There are now 18 states available so you can locate an ancestor by their name. The massive effort by volunteers to index, get in digital searchable format the necessary information and then proof it has been part of the U. S. 1940 Census Community Project. This to date completed collection represents about 75 million people on the 1940 Census. Not all states are done and there is much work still to be completed. Once the searchable indexing is completed on additional states, those will be released.
The states now accessible online to search for your ancestors include: Florida, Mississippi, New Hampshire, Delaware, Nevada, Hawaii, Kansas, Wyoming, Oregon, Vermont, Alaska, Utah, Colorado, Idaho, Arizona, Louisiana, Virginia and Montana. This represents quite a collection and surely most researches had ancestors in 1940 in one or more of these states. If even you don’t believe they lived in any of the 18 now available, check it out anyway, especially is you believe they were in a neighboring state solely, you could be astonished.
Another way researchers are surprised by some finding is when a relative is visiting for any length of time another relative or a family friend in another state. That would have been common for a person, especially a female to go for a visit or to care for another relative for several weeks in a different location. Then you have some relatives who were working in another state in April 1940 or attending school. So never base a selection of a state to search on where their hometown was or where you thought they actually lived, there might be surprises.
Look for siblings of grandparents, aunts, uncles and parents; there can be new information gathered in finding them. Long time family friends are often overlooked. Locate them on the 1940 Census and see who their neighbors were, it might direct you to locate a family member you were not aware of to date.
So launch your investigation, this is a fine collection to start with to find your ancestors.