The major county highways are built on a grid. East–west-oriented roads have a three-digit number beginning with the number "4" and ending in an even number. The further north the road, the lower the number; the further south, the higher the number. North–south-oriented roads have a four-digit number beginning with "10" and ending in an odd number. The further west the road, the lower the number; the further east, the higher the number.