(Updates with "American Idol" earning a 6.4 according to latest ratings released this afternoon. That is still an all-time low for a season finale.)
"American Idol" had its lowest-rated season finale ever Wednesday, sliding in total viewers and the advertiser-coveted 18-49 demographic from past finales.
The finale caps a difficult season for the show, the highest rated on televison for the previous eight seasons. Because of the ratings slip this season, its eleventh, it is in a close race with NBC's "The Voice" for TV's highest-rated program aside from NFL football.
"The Voice" averaged a 6.1 rating in the key demo this season, and the "Idol" average was close to that. "Idol" was expected to average a 6.1 or 6.2, though the final "Idol" average was not yet available Thursday because not all viewing had been factored in.
The "Idol" finale delivered a 6.4 rating/18 share in the key demo -- 22 percent lower than the previous low, the 8.2 in the demo for the season 9 finale. It was 30 percent lower than last season's finale, which had a 9.2 rating.
"Idol" had 21.5 million total viewers, the least ever for a season finale. The previous low was 23 million for the first season finale.
Despite the slide, "Idol" was easily Wednesday night's top-rated and most-watched show, and won the night for Fox. "Idol" also scored its highest ratings in the demo since the second week of this season and its second-highest number of total viewers since the season premiere.
After ratings fell in season 9, "Idol" successfully rebuilt itself in season 10 with new judges Jennifer Lopez and Steven Tyler. There has been speculation that Lopez may not return next season, fueled in part by her declining to publicly commit to the show.
NBC gave "The Voice" a ratings boost this season by airing its premiere episode after the Super Bowl. It will begin its third season in the fall.
This season has been a tough one for aging reality behemoths from "The Bachelor" to "Dancing With the Stars," which have also suffered ratings declines.
As for the other networks:
ABC was second to Fox in ratings and total viewers, averaging 2.6/7 and 7.3 million, according to preliminary ratings. It had its lowest-rated finales for "The Middle" and "Modern Family," which were both down 5 percent from last year in the ratings. At 8, "The Middle" had a 2.0/7 and 6.5 million total viewers. A "Modern Family" repeat aired at 8:30, followed by the show's finale, which had a 4.0/11 and 10 million. The "Apt. 23" finale at 9:30 had a 2.5/7, up 32 percent from last week's season low, and 5.7 million. The "Revenge" finale at 10 had a 2.4/6, up 20 percent from last week's season low, and 7.6 million.
CBS, which aired repeats throughout the night, was third in ratings and total viewers, averaging a 1.5/4 and 5.9 million.
NBC was in fourth, averaging a 1.4/4 and 5.4 million. The "Off Their Rockers" finale at 8 had a 1.5/5 and 5.5 million total viewers, and the "Law & Order: SVU" finale at 10 had a 1.9/5, up 12 percent from last week but down 34 percent from last year's finale. It was the show's lowest-rated finale ever. It had 7 million total viewers.