The inauguration of Barack Obama is causing widespread broadcast media to cover the event, even cable networks as diverse as BET, TV One, Al Jazeera and ESPN.

It would not be a stretch to say that this could be the most widely watched inauguration in US history. The record, so far, is 42 million who tuned in to see Ronald Regan's first inauguration January 20, 1981.

If you love American history, this is the Super Bowl, and it caps a Super Bowl political season, sad NBC News anchor Brian Williams.

The networks coverage is ad-supported but ads will not be as plentiful as during regular programming.

ABC coverage sponsored by Audi will not include commercials. CNN will go commercial-free at 11 a.m. and into the afternoon. MSNC will not take commercial breaks before or after the noon swearing-in but will carry a normal load of ads later.