Growth is brisk but slower than expected, causing automakers to question their multibillion-dollar investments in new factories and raising doubts about the effectiveness of federal incentives.
Carmakers are anxious to keep costs down as they ramp up electric vehicle manufacturing, while striking workers want to preserve jobs as the industry shifts to batteries.
The union targeted three factories: one run by General Motors, one by Ford and one by Stellantis. Prolonged walkouts could hurt the U.S. economy and President Biden.