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.