The Spanish midfielder played in the second half in San Jose after goals from Juan Mata, Memphis Depay and Andreas Pereira sealed the victory.
The Red Devils have won successive games in the United States on their summer tour ahead of the first Premier League game at Old Trafford on 8 August.
And Herrera was impressed with the American support as Louis van Gaal’s continued to build up towards their season-opener against Tottenham Hotspur.
Herrera wrote on his Instagram page: “Second victory in the #MUTour. We keep adding minutes. The fans we have in America are amazing! Thanks to all of you!”
Herrera played a key role in helping the Red Devils secure a top-four finish in the Premier League and a route back into the Champions League last season.
He scored six goals and made four assists in 26 top-flight games for United and particularly clicked into gear in the second half of the campaign.
Manchester United kick off their 2015-16 Premier League campaign with a home clash against Tottenham Hotspur on 8 August.
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