You've probably seen these types of census before, where they are used to count the amount of people living in a household, living in an area, state, country, whether there has been an increase or decrease. Can't recall to an absolute certainty, but this looks like the first time the game industry has ever done a census on itself.

From the article:

The CMP Game Group’s Game Developer Research division has revealed its first-ever Census - determining, through in-depth research, the number of people working within video game development and publishing in North America.

The key findings of the Census include the fact that there are more than 39,700 professionals developing or publishing games within the United States, with more than 8,100 professionals doing so across Canada.

More than 46% of all of those creating games within the United States (around 18,300 employees) are based in California, with Washington (11.63%) and Texas (7.37%) rounding out the top three states. In total, seven states (also including New York, Massachusetts, Illinois, and Florida) have more than 1,000 game professionals working in them.

Read the full article over at gamasutra.com