Most statistics regarding the growth of California's highway system focus on state-owned highways.
A majority of the total mileage owned by Caltrans, and thus comprising the state highway system, are actually two lane roads like Highway One on the Pacific coast and function as both local streets and main streets for many small towns throughout California. Yet it doesn't include other freeways and expressways under the jurisdiction of city and county governments. A much more useful classification for different types of roadways is provided by the Federal Highway Administration based on usage, design and traffic levels. The state highway system includes all the Interstate highways and some pieces of every other type of classification of roadway.