the major county highways are set up on a grid. east–west-oriented roads have a three-digit number beginning with the numeral "4" and ending in an even digit. 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 digit. the further west the road, the lower the number; the further east, the higher the number.