What is the Actual Size of a Four-by-Four Board?

This may seem like a dumb question to some, but a couple of not-so-smart people are suing Home Depot and Menards over this.

Yes, you read that right. According to USA Today, a class-action lawsuit was filed against the two retailers for misrepresentation of lumber sizes. USA Today says,

The alleged deception: Menards and Home Depot market and sell the hefty lumber as four-by-fours without specifying that the boards actually measure 3½ inches by 3½ inches.

What?! A four-by-four isn't 4 inches by 4 inches?! That's Ludacris. (Sarcasm, if you couldn't tell.)

Do they not offer shop class in school anymore? I remember learning this in eighth-grade shop. Actually, my father taught me this earlier than that.

Heck, even the less internet savvy people would know to Google it. Or check Wikipedia, they have a nifty table showing the dimensions.

The next thing they'll try to tell us it; ice is actually frozen water.