MONTPELIER, Vt. (AP) – More than 600 people spanning nearly half a mile marched into Burlington on Monday in what organizers said was the country’s largest global warming demonstration to date.

Carrying signs and banners, marchers called for political action to address climate change.

Monday was the final leg of a 49-mile trek from Ripton that started Thursday. Several hundred people marched each day, with some camping at night, organizers said.

The crowd grew on Monday as it made its way along busy U.S. Route 7 into the state’s largest city, where a rally with speeches by political candidates was planned.

“I started working on climate change almost 20 years ago,” said organizer Bill McKibben, an author who first wrote about global warming in his 1989 book “The End of Nature.”

“This morning is the single most hopeful I’ve been in that 20 years. just to see the unbelievable level of response,” he said of the group that started in Shelburne.

Organizers said the demonstration drew a far larger crowd than expected because global warming is a concern for many Vermonters.

“We’re hoping to insight political action on global warming,” said Rebecca Sobel, state organizer of the Project HotSeat campaign for environmental activist group Greenpeace. “The time for research in the science of global warming is over. We need solutions and we need them now. The technology is already there. We need politicians to help implement it.”

At the rally in Burlington, organizers planned to ask political candidates to back legislation introduced by Sen. James Jeffords, I-Vt., which includes large reductions in greenhouse gas emissions.

Organizers called for increasing fuel standards for cars to 40 miles per gallon and getting 20 percent of the country’s electricity from renewable sources.