At John McCain's rally in the town of Lee's Summit, Mo., there were more people standing outside than were able to fit inside.
That kind of crowd just hadn't been seen at McCain's events before last week's Republican convention.
Saturday in Colorado Springs, about 10,000 people waved American flags at McCain's rally in an airport hangar there, and Friday in the town of Cedarburg, Wis., there were more people crowding the main street and the surrounding blocks than the population of the tiny town.
These numbers seemed unfathomable to the campaign just last month.
So what happened?
Two words: Sarah Palin.
A typical McCain event before he announced the Alaska governor as his running mate averaged only about 1,000 people. Now 5,000 has been the low end of turnout in the last few days, and the biggest event last weekend drew about 11,000.
These are crowd sizes that are pretty typical for the Obama-Biden campaign, before and after the conventions. There were about 10,000 at an Obama-Biden event in Lancaster, Pa., last week, and more than 12,000 estimated at the Democrats' event in Battle Creek, Mich., earlier in the week.
But there have been unusually big crowds for the Republican ticket this year.
"Isn't this the most marvelous running mate in the history of the nation?" McCain asked the Wisconsinites Friday morning one the Republican ticket's first day of barnstorming after the convention. "Sarah Palin -- she's magnificent."
The Arizona senator's pick for a running mate seems to be a huge hit within the party. Homemade signs about Palin were seen in greater numbers in Missouri than were signs for McCain.
Cheerleaders from a high school in Albuquerque, N.M., Saturday night launched a Palin cheer while warming up the crowd -- but no such cheer went out for the presidential candidate.
Crowds at all of this weekend's stops found cause to interrupt the proceedings with chants of "Sar-ah! Sar-ah! "
McCain seemed enthused too.
"I could not ask for a greater partner than the governor of Alaska, Sarah Palin..." McCain told the crowd in Albuquerque, Saturday night. "Because the response, the response to her has been overwhelming, it's been incredible, she's ignited America. I'm so proud to have her with me."
So proud, in fact, that McCain asked her to stay on and campaign together a little longer than previously scheduled this week. Palin had planned to head off to campaign on her own in swing states before heading back to Alaska for a few days. But the joint road trip has been extended.
"We're having a good time, he's enjoying campaigning with her and he just wanted to extend it," senior McCain adviser Mark Salter told ABC News. "Obviously we know we've got to cover a lot of real estate, and that will always be the case."
"They're good campaigners together, [but] you can't do that entirely for the next two months obviously," Salter said.
Palin will leave McCain's side midweek to head home for a few days and sit down for her first major interview with ABC News' Charles Gibson. When she resumes campaigning, it will likely be without her running mate by her side, for now.
Actor Robert Duvall claimed to have known about Palin all along. At the New Mexico event, he was on hand to cheer on the new political couple.
"About a year ago I first saw this wonderful woman speak," the veteran of "Lonesome Dove" and the "Godfather" movies said. "I didn't know who it was. And I said who is this woman? And a year later, I said to myself about three or four weeks ago, why isn't she up for the vice presidency?"
ABC's Jake Tapper and Sunlen Miller contributed to this report.