State law concerning state highways underwent major changes in 1923. State highways were referred to as state roads. Most state roads were assigned numbers as well as names. It was probably around this time that state highway route number signs were first posted. Certainly, maps of Washington State published for use by the general public were using these state road numbers by the mid 1920s.
Athough Wisconsin had started posting state route numbers as early as 1917, it was not until 1926 that a national highway numbering system was devised. Most major national highways had names and were identified with so called trail blazer signs often painted on telephone posts along highways. This system of marking highways had originated with the Lincoln Highway between New York City and San Francisco in 1911. By the mid 1920s, several national trails had been established by many highway related promotional groups. Many of these routes overlapped. The system had become quite confusing by the mid 1920s. The American Association of State Highway Officials (AASHO) came up with a numbered system of United States highways in 1926. The US numbered shields replaced the trail blazer markers, although some of the old national trail names continue in use as local street and road names to this day.
In Washington State, the state road names and numbers continued to be used in state law and Department of Highway documents after 1926 but US route number signs replaced state road number signs along state roads that were designated as US routes. Thus State Road 1 Pacific Highway became signed as US 99, State Road 2 Sunset Highway became signed as US 10, etc.
The next major change to the state highway system took place in 1937 with the introduction of the Primary and Secondary State Highway systems.
Links to individual state roads:State Road 1-Pacific Highway
Primary State Hwys Secondary State Hwys