Functional Classification



County Road - Other Principal Arterial

MiA 2

County Road - Minor Arterial

MaC 2

County Road - Major Collector


County Road - Minor Collector

Loc 2

County Road - Local

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Map Information

The above map displays functional classification of County-maintained roads, as designated by the State of California. NOTE: Roads that are within city limits, state highways, or private property do not belong to the County-Maintained Road System.

Functional Classifications

Other Principal Arterials

  • Serve major centers of metropolitan areas, provide a high degree of mobility and can also provide mobility through rural areas.
  • Unlike their access-controlled counterparts, abutting land uses can be served directly. Forms of access for Other Principal Arterial roadways include driveways to specific parcels and at-grade intersections with other roadways.
  • Unlike Interstates and Other Freeways & Expressways, there are usually multiple Arterial routes serving a particular urban area, radiating out from the urban center to serve the surrounding region. In contrast, an expanse of a rural area of equal size would be served by a single Arterial.

Minor Arterials

  • Provide service for trips of moderate length, serving geographic areas that are smaller than their higher Arterial counterparts and offer connectivity to the higher Arterial system.
  • In an urban context, Minor Arterials interconnect and augment the higher Arterial system, providing intra-community continuity and may carrying local bus routes.

Major Collector & Minor Collectors

  • Function to gather traffic from Local Roads and funnel them to the Arterial network.
  • In the rural environment, Collectors generally serve intra-county travel (rather than statewide) and constitute those routes on which (independent of traffic volume) predominant travel distances are shorter than on Arterial routes. Consequently, more moderate speeds may be posted.
  • Collectors are divided between two categories: Major Collectors and Minor Collectors. Major Collectors generally have a higher level of usage than minor collectors. Major Collectors are eligible for federal funding, whereas Minor Collectors are not.

Local Roads

  • Account for the largest percentage of all roadways in terms of mileage.
  • Not intended for use in long distance travel, except at the origin or destination end of the trip, due to their provision of direct access to abutting land.
  • Often designed to discourage through traffic.
  • As public roads, should be accessible for public use throughout the year.
  • Transit routes usually do not run on Local Roads

Contact Information

Business Hours
Monday – Friday
8:00 AM – 5:00 PM
Contact us by Phone
Office Location
La Plaza B
2300 County Center Drive
Suite B 100
Santa Rosa, CA 95403
38.462023, -122.725381