DETROIT — The United Auto Workers gave final approval Friday for a new four-year labor contract with General Motors. The ratification brings to an end the union's 40-day strike, which cost the automaker well over $2 billion.

Some of the union's 48,000 members with GM are expected to return to work as early as Saturday, showing the automaker is wasting no time in recouping lost production from the work stoppage, which started Sept. 16.

The contract was supported by 57% of members who voted, according to final results from the union. Less than 41,000 of the UAW's roughly 48,000 workers with GM cast ballots.

GM CEO and Chairman Mary Barra, in a statement, said the deal recognizes the company's employees for "the important contributions they make to the overall success of the company, with a strong wage and benefit package and additional investment and job growth in our U.S. operations."

GM shares were up about 1% during after-market trading following reports of the ratification. The stock closed at $36.74, up 2.57%.

The union on Friday said it will negotiate with Ford next, followed by Fiat Chrysler. Both companies had agreed to contract extensions so the union could concentrate on talks with GM. The union will use the GM deal as a template for negotiations with the other Detroit automakers.