Winless against its arch rival since 2001, Canada dropped its latest contest — a friendly between the two nations on Friday night — 1-0 on a goal by Canadian-born Sydney Leroux.
"We're disappointed because we're sick of saying 'good try,' 'well done,' and 'we battled hard,'" Herdmann said. "At some point we've got to beat this team and if it's not now, then when? And hopefully it's (at the Women's World Cup) in 2015."
Leroux, who is a U.S. citizen, scored in the 78th minute to break a scoreless tie against Canada and give the U.S. the victory in both teams' 2014 opener.
It was Leroux's fourth goal in the past three games, with two of them coming against the country of her birth.
"I love to watch her," Herdmann said. "She's a phenomenal player and she's great to watch ... and she scores against us. I've just told her (after the game) to stop doing that, man. You do it against anyone else but not us."
The game looked as if it was going to be a scoreless draw before Leroux's late offence, largely thanks to strong play by Canadian goalkeeper Erin McLeod and no clear goal chances for the U.S.
"I always hope that we're going to get one," said Leroux, who was stopped several times in the first half.
"That's kind of how we play, and we push to the very last second. I'm just happy that we came out on top of the game 1-0. It was a good game. It was physical and I'm glad we came out on top."
The Americans sent plenty of chances into the zone, but McLeod calmly caught and parried several crosses. But in the 78th minute, a bit of nifty footwork gave the U.S. the lead.
Becky Sauerbrunn started a run with the ball outside the 18-yard box, fed the ball to substitute Christen Press and then immediately got it back, going toward the right post.
Press then weaved a pass through McLeod and defenders Kadeisha Buchanan and Sura Yekka to find Leroux waiting all alone 3 yards.
Leroux one-timed the ball with the inside of her left foot for the game-winner.
The Americans extended their home unbeaten streak to 78 games (68-0-10).
The U.S., ranked No. 1 in the world, also remains undefeated under second-year coach Tom Sermanni (14-0-3), and is a perfect 11-0 all time when playing in Texas.
The win marks a strong start to a World Cup qualifying year for the Americans. CONCACAF qualifying is at the end of the year, and the U.S. should be favourites to emerge out of the region.
Canada, the hosts the 2015 Women's World Cup, automatically qualifies for the tournament.
The 20,862 fans at FC Dallas' home stadium were the largest crowd since 2003.
"I was a bit anxious about this game because we haven't played a game for a long time," said Sermanni, whose team hadn't played since a 4-1 victory against Brazil.
"The players have had time off. Canada has played some international recently."
The Americans thought they took the lead in the 38th minute when defender Whitney Engen popped in a headed pass, but she was called offside by about 6 yards.
Canadian midfielder Josée Bélanger took possession at the top of the U.S. zone moments after Engen's offside and dinked the ball through two American defenders to Diana Matheson.
U.S. goalkeeper Hope Solo cut down the angle and Matheson's cross-body chip from about 6 yards trickled past the far post to preserve the scoreless half.
It was Solo's only test of the first half, and she didn't have to make a save until diving to her right in the 87th minute to stop Jonelle Filigno and preserve the shutout.
"You know they're going to score," Herdmann said. "I've never known a game where the U.S. doesn't score."