Does a slow moving tractor have to let other motorists pass?

In most jurisdictions, yes, a slow-moving tractor must let other motorists pass. For example, in the United States, the Federal Motor Carrier Safety Administration (FMCSA) requires slow-moving vehicles, including tractors, to pull over and allow faster-moving vehicles to pass when they are impeding the flow of traffic. State laws may also have specific regulations regarding slow-moving vehicles, so it is important for drivers to be familiar with the laws in their jurisdiction.