In the counties that use 600-series numbers, the selection of this range was coordinated within the state[citation needed], gradually replacing older systems of mainly one- and two-digit routes.

[1] With very rare exceptions (such as County Route 537), the 500 series follows the rule of cardinal direction used for Interstate Highways and U.S.

County route numbers have not wholly replaced the preexisting names of the local roads to which they were assigned.

Street signs at major intersections will denote both the local road name and the county route number if it has one.

[citation needed] In February 1942, a group of civil defense routes was assigned with numbers in the 500s in New York, New Jersey, and Connecticut.

These roads were designed as through routes for civilian use in case the state highway system was needed by the military during World War II operations.

The only 600 signage to appear in Ocean County has been put up as a result of recent construction projects, which can cause confusion for those not familiar with the area.

As every piece of New Jersey is part of an incorporated municipality, every road not designated a county or state route is locally maintained.