United Automobile Workers (UAW) union members walked out of their jobs at General Motors on Monday, the union's first national strike since 2007.
Members had voted Sunday morning to strike after contract negotiations broke down.
More than 45,000 striking workers managed to shut down 33 manufacturing plants in nine states across the U.S., as well as 22 parts distribution warehouses.
Terry Dittes, UAW's GM head, said the union is standing up for fair wages, health care and job security.
“We stood up for General Motors when they needed us most. Now we are standing together in unity and solidarity for our members, their families and the communities where we work and live,” Dittes said Saturday.
It is unclear how long the walkout would last.
GM has said it offered more than $7 billion in investments, more than 5,400 jobs and improved wages and benefits in negotiations that began after the union contract expired midnight Saturday.
Talks were slated to restart at 10 a.m. Monday, according to an Associated Press report.