My uncle is a judge in the circuit court. This requires him to travel to diffferent locations to ensure wide visibility and understanding of cases within a region
That's cool!  What does a judge in the circuit court do?
He just has to travel a lot to make sure there is a wide visibility of the cases. Back in the days, the judges actually traveled on horseback! 
How large of an area does he have to travel?  Just within a single city, county, state or nation wide?
of a local judiciary. Most of these local judicial circuits (that is, in terms of the actual routes traveled by judges) have been thus replaced by judges regularly stationed at local courthouses, but in many areas, the legacy term remains in usage.
England and Wales.
England and Wales is divided into six regions or "circuits" for the purposes of the administration of justice. 
- Northern Circuit
- North Eastern Circuit
- Wales and Chester Circuit (also known as Wales and Cheshire)
Circuit court
Circuit courts are court systems in several common law jurisdictions. The core concept of circuit courts requires judges to travel to different locales to ensure wide visibility and understanding of cases in a region. More generally, some modern circuit courts may also refer to a court that merely holds trials for cases of multiple locations in some rotation.
History.
King Henry II instituted the custom of having judges ride the circuit each year to hear cases, rather than requiring every citizen to bring their cases to London (see