If you operated a trucking service between san francisco, california, and portland, oregon, could you be subject to regulating by either or both of the states and the federal government

Regulations need to be followed from both states and the federal government.

Each state can set regulations because business is happening in each state. You would also need to follow federal regulation because you are crossing state lines to conduct business.

The federal regulations are typically fewer in number and scope but would create general guidelines for running the business. Due to federal power being superior to state power, all federal regulations would take priority over the state regulations. The states could each regulate business in addition to the federal regulations. Therefore state regulations tend to be more precise.