All you public affairs junkies out there should take a moment today to wish C-SPAN a happy 30th birthday.

And, according to a Hart Research survey sponsored by the channel, there are a lot of your out there. One in five cable TV households, or about about 39 million Americans, watch C-SPAN a least once a week. Perhaps most impressive, nine in ten of those viewers said they voted in 2008.

Date the U.S. House of Representatives goes on TV and the cable industry launches C-SPAN to 3.5 million homes: March 19, 1979.

First U.S. Representative to speak on the House floor as C-SPAN