Final answer:
The US Supreme Court case that upheld restrictions on women's working hours is Muller v. Oregon.
Step-by-step explanation:
The US Supreme Court case that upheld restrictions on women's working hours is Muller v. Oregon. In this case, decided in 1908, the Court upheld an Oregon state law that limited the working hours for women to 10 hours a day. The decision was based on the belief that women need special protection in the workplace due to their reproductive role and that long hours could have negative effects on their health and well-being.