The National Archives released for the first time yesterday individual records from the 1940 Census – unleashing an online treasure trove of 3.8 million pages eagerly awaited by genealogists and researchers.

The country has changed substantially in 72 years: Its population has ballooned to nearly 309 million from 132 million. Alaska and Hawaii were not yet states. California's entire population, 6.9 million, was less than Los Angeles County's today.

California's population in 2010, more than 37 million, was the nation's largest. In 1940, it was the nation's fifth-largest, trailing New York, Pennsylvania, Illinois and Ohio. But California led the nation in other ways, including educational attainment.

While just 24.5 percent of Americans had earned at least a high school diploma in 1940, more than 37 percent of Californians had – the highest rate in the country. It also had the highest rate of college graduates among states, 6.8 percent, and was bested only by Washington, D.C.'s 11.1 percent.

In 2010, 80.7 percent of Californians were high school graduates and 30.1 percent held at least a bachelor's degree. While higher than in 1940, those rates are no longer the nation's highest: 85.6 percent of Americans now have at least high school diplomas, and 28.2 percent are college graduates. Wyoming has the nation's highest rate of high school graduates, 92.3 percent, and Massachusetts has the highest rate of college graduates, 39 percent.