More than 19 million Americans watched at least part of the 12-12-12: The Concert for Sandy Relief on Wednesday.

Nielsen said Friday that 19.3 million viewers in the U.S. tuned in to at least a portion of the concert, which aired on 15 channels that are rated by the company. The average audience viewing at any given moment was 5.2 million viewers.

The concert, which aired live from 7:30 p.m. ET until about midnight, also was carried on some smaller channels that are not rated by Nielsen.

Organizers told The New York Times that there were millions of Web streams during the concert, but those were not included in the Nielsen figures.

The concert was “the most widely distributed live musical event in history,” according to Nielsen, with nearly 2 billion people around the world able to access it via TV, radio and the Internet.

The event, which was held at New York’s Madison Square Garden, featured a slew of A-list performers including Paul McCartney and Nirvana, the Rolling Stones, Bruce Springsteen and the E Street Band, Kanye West and Alicia Keys along with appearances from Kristen Stewart, Billy Crystal, Chris Rock, Jon Stewart, Stephen Colbert and Jimmy Fallon, among others. [Billboard.biz]