C0L0PH0N writes: The National Archives has published the entire 1940 US Census, totaling 18 terabytes. This will be a treasure trove for decades for genealogists and social researchers and is completely free for everyone. The US Census population in 1940 was 134 million, compared to 308.7 in 2010. The median age in 1940 was 29.0 years, compared to 37.2 in 2010. Oh, and you can order your private digital copy for a mere $200,000.