The code also allows county highways to be freeways or expressways. Counties are also permitted to designated expressway systems, and counties may work together to coordinate county highways. All county highways which for a period of five consecutive years are impassable for vehicular travel, and on which during such period of time no public money is expended for maintenance, are considered to be unnecessary highways, and may be redesignated as stock trails. This program had the bulk of its routes added between 1958 through 1970. There have been no new county sign routes added since 1983.
Counties also maintain internal road numbers.
Sometimes these numbers are reflected on the county roads, for example, in Tulare County, County Road SR140 is signed Road 140. This county has no routes in the County Signed Route program. This county has no routes in the County Signed Route program. This county has no routes in the County Signed Route program. This county has no routes in the County Signed Route program.