(Adds latest Nielsen figures)
NEW YORK, Oct 5 (Reuters) - An estimated 37 million Americans watched the U.S. vice presidential debate between Republican Mike Pence and Democrat Tim Kaine on television, according to Nielsen data on Wednesday, less than half the number who tuned in to Donald Trump's first matchup with Hillary Clinton last week.
The figure represented the average audience across nine channels during Tuesday's 90-minute encounter. Broadcaster NBC pulled in the biggest audience with 7 million viewers. Fox News Channel led cable networks with 6.1 million.
Last week's first debate between the presidential candidates for the Nov. 8 election, Republican Trump and Democrat Clinton, was watched by a record 84 million TV viewers.
Vice presidential debates have traditionally attracted smaller TV audiences, with the exception of the 2008 encounter between Democrat Joe Biden and Republican Sarah Palin, which set a record for a VP debate of 69.9 million viewers.
The 2012 vice presidential encounter between Biden and Republican Paul Ryan was watched by 51.4 million Americans.
None of the figures for the debates include those who watched online, through social media, or in bars and restaurants.
Tuesday's 90-minute face-off between Pence, governor of Indiana, and Kaine, a U.S. senator from Virginia, was the only debate between the vice presidential contenders before the election next month.
NBC is a unit of Comcast Corp. Fox News Channel is owned by 21st Century Fox. (Reporting by Jill Serjeant in New York; and Lisa Richwine in Los Angeles; Editing by Frances Kerry and Jonathan Oatis)