Road function classes
Last checked against the NHTSA pages:
The Federal Highway Administration puts each public road in a class by the service it gives. FARS records the class of the road of each crash. The county, state and year pages of this site show the fatal crashes on each class.
The class of a road by the service it gives, from Interstate to local road. The Federal Highway Administration defines the classes. FARS records the class of the road of each crash.
This data element identifies the functional classification of the segment of the trafficway on which the crash occurred.
| Class | What it is | Fatal crashes | Share |
|---|---|---|---|
| Interstate | A limited access divided road of at least four lanes in the Interstate System. | 44,809 | 12.6% |
| Other freeways and expressways | An urban principal arterial with limited control of access that is not an Interstate. | 15,797 | 4.4% |
| Other principal arterial | A major street or highway for high-volume traffic between major places. | 106,218 | 29.8% |
| Minor arterial | A street or highway that links cities and larger towns, or spreads trips to small areas. | 78,624 | 22.1% |
| Major collector | A collector. In rural areas it serves travel inside a county. In urban areas it gives access to neighbourhoods and arterials. | 55,313 | 15.5% |
| Minor collector | A collector. NHTSA has one entry for major and minor collectors. | 12,241 | 3.4% |
| Local | A street whose main purpose is to feed higher classes and to give direct access. | 43,490 | 12.2% |
The shares are of the crashes with a reported class. A share does not compare the roads by traffic or by length.
FARS gives the class from 2015. A crash with no reported class is not in the shares.
The words of NHTSA
These are the definitions of the classes on the page "Terms" of the FARS Encyclopedia. NHTSA sets each word of that page with a capital letter, and the quotations keep it.
- Interstates.
Limited Access Divided Facilities Of At Least Four Lanes Designated By The Federal Highway Administration As Part Of The Interstate System.
- Other Freeways And Expressways.
All Urban Principal Arterial With Limited Control Of Access Not On The Interstate System.
- Other Principal Arterials.
Major Streets Or Highways, Many With Multi-lane Or Freeway Design, Serving High-volume Traffic Corridor Movements That Connect Major Generators Of Travel.
- Minor Arterials.
Streets And Highways Linking Cities And Larger Towns In Rural Areas In Distributing Trips To Small Geographic Areas In Urban Areas (not Penetrating Identifiable Neighborhoods).
- Collectors.
In Rural Areas, Routes Serving Intra-county, Rather Than Statewide Travel. In Urban Areas, Streets Providing Direct Access To Neighborhoods As Well As Direct Access To Arterials.
- Local Streets And Roads.
Streets Whose Primary Purpose Is Feeding Higher Order Systems, Providing Direct Access With Little Or No Through Traffic.
Source: NHTSA, FARS Encyclopedia, Terms, copied on 2 October 2026.