• by Wayne Friedman , January 21, 2009

Tuesday's inauguration of President Barack Obama recorded the second-best viewing of a presidential induction ever. Later that night, inauguration festivities helped pull down "American Idol"'s typically big viewing numbers.

Nielsen Media Research said about one-third of U.S. homes--a 25.5 rating, some 37.8 million Americans--watched the presidential inauguration during the daytime, the biggest numbers in nearly 30 years. The 37.4 household rating--41.8 million viewers--of President Reagan in 1981 ranks as the highest viewing numbers ever for an inauguration.

Obama's figures have yet to include expected millions via the Internet, including CNN.com, FoxNews.com and MSNBC.com. The Obama Inauguration was seen on some 15 traditional broadcast and cable TV networks. The Reagan numbers came from just three networks: ABC, NBC, and CBS. The lowest numbers for a presidential start-up were in 2005 for the second inauguration of George W. Bush, at some 15.5 million viewers.

Into the evening, the presidential festivities cut into the typical double-digit "Idol" ratings numbers among 18-49 viewers. The big Fox show moved down to a Nielsen preliminary 9.0 rating/22 share from an 11.8/28, the week before, its season premiere. ABC's two-hour "Neighborhood Ball: An Inauguration Celebration" came in at second place, averaging a 3.7/9.

NBC threw up "Biggest Loser" against the night and grabbed a 4.8/11 for its 9 p.m. hour, just ahead of Fox's "Fringe" at a 4.7/11. CBS checked in with an Obama special at 9 p.m., "Change and Challenge: The Inauguration of Barack Obama," which earned a 1.8/4.

At 10 p.m. it was NBC's turn to focus on the new president with "The Inauguration of Barack Obama," which ran against ABC's "A Moment in History: The Inauguration of Barack Obama." ABC won the time period here with a 3.0/7 to NBC's 2.2/6. CBS came in second place at 10 p.m. with a repeat of "The Mentalist."

For the night, Fox still won--thanks to "Idol"'s early evening numbers--with a 6.9/16 for 18-49 viewers and 17.3 million viewers overall. ABC made it just about halfway to Fox's numbers, with a 3.5/8. NBC was right behind with a 3.4/8, followed by CBS at a 2.2/5, Univision at 1.7/4 and CW with a 1.0/2.