Jimmy Zumba, a conservative Latino activist, was volunteering for the Trump campaign in Reading, Pa., in October when he saw them, spreading out by the dozens in the neighborhoods around the city. They were canvassers for the Harris campaign, and there seemed to be legions of them. “It was an army, I tell you,” he said.

In the months leading up to last Tuesday’s election, both campaigns went all in on Pennsylvania, long assumed to be the tipping-point state in a close race. They poured money into the state, saturating the airwaves with ads and staging rallies or appearances in virtually every corner of the commonwealth. But what was supposed to be a key Democratic advantage, particularly in an election that many thought would be decided by a percentage point or perhaps even less, was the ground game.

“They had more money and more resources and more people,” Mr. Zumba said. “To be honest, I was pretty concerned.”

Vice President Kamala Harris did win Reading, a Latino-majority city in the heart of Trump-supporting Berks County, but she took in several thousand fewer votes than Joe Biden had four years earlier when he carried the city — along with the state, and the election.

Ultimately, the movements that decided the election were less tactical than tectonic: a broad dissatisfaction with the state of the economy and a deep unease over immigration and border security. Ms. Harris lost ground compared with Mr. Biden in 2020 in nearly every part of the state — in deeply red and deeply blue counties, in Latino-majority cities, in Pittsburgh, in Philadelphia and even in the suburban counties in the state’s southeastern corner that were supposed to form a Democratic firewall.