As Scotland evolved so the counties and registration districts changed. Ayrshire was no different, probably the most sought period (by genealogy seekers) was when the Sherriffdom of Ayr was the three districts of Kyle, Carrick and Cunninghame which later became Ayrshire. Nowadays for administration it is sub-divided into North, South and East Ayrshire. (there is no west)
Hunterston has it's own section ......